(Adds comments by Representative Mark Walker)
WASHINGTON, Dec 19 (Reuters) - The U.S. Congress is struggling through another contentious week as infighting over defense spending, healthcare and other matters complicates the drive to pass a temporary spending bill by midnight on Friday to avert a partial government shutdown.
In a week when President Donald Trump and his fellow Republicans in Congress are hoping to celebrate the passage of tax overhaul legislation, many in the party showed little appetite for a government shutdown at week's end.
But they sounded resigned to having to navigate through some drama over a package that includes so many disparate components, which could make for a messy process.
"I'm going to vote for whatever I need to, to keep the government open," Republican Representative Chris Collins told reporters.
The last time government agencies had to shut down because Washington could not pay its bills was in October 2013.
Leading Republicans in the Senate and House of Representatives expressed optimism that a funding bill, coupled with a large new disaster aid package, would pass by Friday's deadline.
But some were predicting that lawmakers would bump right up against the cutoff.
The House could vote as soon as Wednesday on legislation that extends most funding for domestic programs through Jan. 19. Democrats are likely to mainly oppose the bill, arguing that their priorities are being ignored.
Conservative Republicans are insisting on higher military funding through the rest of the fiscal year ending on Sept. 30 as part of the House bill.
Democrats in the Senate are expected to block that formula if, as expected, it does not also have more money for non-defense programs.
The House measure would also include $81 billion in disaster funding to help Puerto Rico, the U.S. Virgin Islands and several U.S. states recover from hurricanes, wildfires and other natural disasters. That price tag has made some Republicans uneasy.
Some Republicans are also worried about a Senate strategy to add a bipartisan healthcare proposal to the government funding bill, in keeping with a promise Senate Majority Leader Mitch McConnell made in order to coax Republican Senator Susan Collins to vote for the tax legislation.
Conservative House Republicans do not like the bipartisan healthcare proposal because it would fund subsidies for low-income participants in the Obamacare health insurance program, and does not include language that restricts federal funds for abortion.
McConnell's promise to Collins "means squat over here," said Representative Mark Walker, chairman of the Republican Study Committee, the largest group of conservatives in the House. Some conservatives may vote against the funding bill in protest, he told reporters outside the House.
The House bill also would extend the Children's Health Insurance Program for five years.
If Democrats continue to withhold their support for the stopgap spending bill and some Republicans peel off, Congress could find itself struggling to pass a bill as the clock ticks toward midnight on Friday.
(Reporting by Richard Cowan and Susan Cornwell; Editing by Jonathan Oatis and Peter Cooney)