Washington (CNN) -- House Republicans pushed through a spending plan early Sunday morning that would delay Obamacare for a year and repeal its tax on medical devices.
The vote makes the chances of a government shutdown Tuesday increasingly likely.
That's because passage of the amendments sends a temporary budget resolution back to the Senate, where Democrats vow to again block the anti-Obamacare amendments.
President Barack Obama has added a veto threat to that position.
Without a deal, a government shutdown will begin at 12:01 a.m. Tuesday.
A Senate Democratic source told CNN there were no plans to convene the Senate before Monday, when the current fiscal year ends.
The decision to vote on the House amendments Saturday night emerged from a rare weekend GOP caucus meeting called by House Speaker John Boehner.
The votes, taken after midnight, were 232-192 for the Obamacare delay, and 248-174 for the medical device tax repeal, mostly along party lines.
Two Democrats voted for the Obamacare delay: Mike McIntyre of North Carolina, and Jim Matheson of Iowa.
Seventeen Democrats voted for the tax repeal.
Meanwhile, a bill to guarantee pay for military personnel during any shutdown passed 423-0.
Partisan back and forth
Senate Majority Leader Harry Reid called the Republican strategy "pointless" and said the Democratic-led Senate would reject the GOP alternatives, while the White House said Obama would veto the House proposal if it reached his desk.
A separate White House statement said voting for the GOP measure "is voting for a shutdown."
The partisan back and forth over the spending plan -- called a continuing resolution in legislative jargon -- came after the Senate on Friday restored funding for Obamacare that House Republicans stripped from their original version and sent the proposal back to the House.
Boehner convened his caucus on Saturday to forge a counteroffer to the Senate changes.
House Republicans said they wanted the following:
-- an amendment that will fund the government until December, a month longer than the Senate version.
-- stop as much of the president's health law as possible.
-- repeal the medical device tax because they said it was sending jobs overseas.
-- a "conscience clause" to the one-year delay amendment to allow employers and insurance plans to refuse to cover birth control.
Military pay in a shutdown
Showing that the House Republicans don't expect the Senate to accept their changes, House leaders held a separate vote to ensure that the military gets paid in the event of a government shutdown.
Officials estimate the military pay could be affected by a shutdown as soon as October 14, and the GOP move was considered a political gesture to shield the party from criticism that its brinksmanship could hurt U.S. fighting forces.
In further evidence of the political nature of the separate military pay proposal, Democratic Rep. Chris Van Hollen of Maryland said Democrats would likely support it.
On the spending plan, though, Reid said the Republican tactics amounted to what he described as extortion by "tea party anarchists."
"To be absolutely clear, the Senate will reject both the one-year delay of the Affordable Care Act and the repeal of the medical device tax," Reid said in a statement. "After weeks of futile political games from Republicans, we are still at square one."
Meanwhile, the White House made clear on Saturday that Obama dismisses any effort to tie provisions undermining Obamacare to the spending measure needed to prevent a government shutdown.
"Republicans have tried and failed to defund or delay the health care law more than 40 times, and they know this demand is reckless and irresponsible," said the statement from White House spokesman Jay Carney, adding that Obama would not negotiate on Obamacare or spending issues "under threats of a government shutdown that will hurt our economy."
Shutdown deadline looms
Reid previously warned that any changes to the Senate's version by the House would result in at least the start of a government shutdown because of the time it would take to reconsider the proposal.
Republican Rep. Michael Grimm of New York said Saturday a "slight" shutdown could occur due to the little time left to pass a short-term spending plan for the new fiscal year that starts Tuesday.
"I'm hoping no, but just look at the timing," Grimm said, laying out a scenario in which the political wrangling leads to last-minute deliberations on Monday and beyond.
The prospect of a government shutdown caused by GOP tactics irked the longest serving member of Congress in history, Democratic Rep. John Dingell of Michigan, who said in a statement that "this once-deliberative body has been taken over by knaves and know-nothings, content with putting partisan politics ahead of the American people."
"I've said before that I believe that this current Congress would be incapable of passing the Ten Commandments or even the Lord's Prayer, and today's actions have only further galvanized that belief," said Dingell, who was first elected in 1955 and is serving his 30th term.
The legislative hot potato involving the spending plan began last week when the House stripped Obamacare funding from the proposal it sent to the Senate.
On Friday, the Senate voted on strict party lines to restore the Obamacare funding and send the measure back to the House.
That left Boehner with the choice of urging his divided Republican caucus to join Democrats in passing the Senate plan or to yield again to the tea party wing that seeks to undermine Obamacare.
Cruz loses filibuster bid
The Senate began its votes Friday by easily overcoming a filibuster led by GOP Sen. Ted Cruz of Texas against the spending plan. Cruz waged a 21-hour floor speech this week against Obamacare, but 25 more moderate Republicans rejected his tactics in voting with Democrats on Friday to move ahead on the measure.
Meanwhile, Democrats facing re-election next year in conservative-leaning states such as Mark Pryor of Arkansas, Mark Begich of Alaska, Mary Landrieu of Louisiana and Kay Hagan of North Carolina all resisted Republican pressure to buck their party over the Obamacare funding.
Responding to the GOP tactics, Obama said Friday that new exchanges for private health insurance under the reforms will open next week as scheduled -- even if there is a government shutdown.
"The House Republicans are so concerned with appeasing the tea party that they have threatened a government shutdown or worse unless I gut or repeal the Affordable Care Act," Obama said, adding: "That's not going to happen."
Democratic Sen. Barbara Mikulski of Maryland said the goal of the short-term spending measure was to provide time to work out a broader spending plan for the rest of fiscal 2014 that would ease the impact of forced cuts to the military and other government programs.
House GOP split
Republican leaders in both chambers don't want a shutdown now over the spending issue, for political and negotiating reasons.
They fear the optics of Republicans being blamed for a shutdown, and also want to exert as much leverage as possible for the GOP's agenda at the upcoming deadline to raise the federal debt limit.
However, Boehner needs backing from the 40 or so tea party conservatives in the House in order to have a spending plan pass with full support from his Republican caucus.
The tea party opposition to the Senate version would mean it could only pass the House with support from all Democrats and some Republicans, which would further weaken Boehner's already shaky leadership of his caucus.
Tea party conservatives want to halt Obamacare now, just as full implementation of its individual health care exchanges begins in the new fiscal year starting Tuesday.
More moderate Republicans, such as veteran Sens. John McCain of Arizona and John Cornyn of Texas, criticize the strategy of tying a government shutdown to undermining the health care reform law passed by Democrats in 2010 and upheld by the Supreme Court last year.
Debt ceiling deadline
The shutdown showdown comes a few weeks before another fiscal deadline -- the need to raise the nation's debt ceiling so the government can pay all its bills.
Treasury Secretary Jack Lew said this week the limit on how much the government can borrow must be increased by October 17 or the nation could be technically in default.
Analysts warn of severe economic impact from any doubt cast over whether the United States would fail to meet its debt obligations. A similar bout of congressional brinksmanship over the debt ceiling in 2011 led to the first-ever downgrade of the U.S. credit rating.
However, Boehner faces the same rift in his caucus over the debt ceiling issue, with tea party conservatives pushing for to undermine Obamacare and fulfill other Republican priorities in return for what Obama calls the responsibility of Congress to make sure America can pay its bills.
On Thursday, Boehner had to delay introducing a GOP debt ceiling plan after conservatives complained the proposed package failed to include enough budget cuts and significant changes to entitlement programs.
The initial proposal by House GOP leaders, which would raise the debt ceiling for a year, included a one-year delay of Obamacare, provisions to roll back regulations on businesses, tax reforms, and approval of the Keystone XL oil pipeline.
House conservatives push Boehner
However, conservatives wanted more.
Republican, Rep. Cynthia Lummis of Wyoming told CNN that she was undecided but wanted to see deeper budget cuts on the measure.
"I came here to cut spending and to reduce the size of the federal government, so when those opportunities arise I want to take advantage of them," Lummis said.
Obama said Friday that the GOP strategy amounts to threatening to "burn the house down simply because you haven't gotten 100% of your way."
"That's not how our democracy is supposed to work," he said, repeating his past insistence that he will not negotiate under threat of a U.S. default because Congress failed to increase the debt ceiling.
White House spokesman Jay Carney told reporters on Thursday a one-year delay in implementing Obamacare's individual mandate for people to obtain health insurance would undermine a key provision of the program that prohibits the denial of coverage due to pre-existing conditions.
"The fact is you have to make the system work," Carney said, adding people with pre-existing conditions won't be denied insurance under Obamacare "because of the expansion of the number of people who will be covered and participate in these marketplaces provided by the Affordable Care Act through the individual mandate."
CNN Chief National Correspondent John King said Thursday that focusing on the debt ceiling was where House Republicans "wanted to wage this fight all along."
"They didn't want to get bogged down in the government shutdown fight," King said, "but a conservative revolt within the House Republican ranks forced them to get there."
CNN's Dana Bash, David Simpson, Jim Acosta, Lisa Desjardins, Ted Barrett and Deirdre Walsh contributed to this report.