All eyes will be on the Senate on Thursday as Republicans seek to chip away at Democratic unity in the high-stakes showdown over the longest government shutdown in U.S. history.

The Senate is poised to hold dueling votes over competing plans to end the 34-day partial government shutdown.

It will vote first on President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE’s weekend proposal that includes money for his wall on the Mexican border and other immigration provisions. The Senate will then vote on a simpler measure that would reopen the government for more than two weeks.

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GOP senators acknowledge that neither proposal will garner the 60 votes needed to advance, underscoring that the shutdown is not ending this week.

But both sides will be watching the vote count closely to see how many members break with their parties and which measure gets the most votes.

Republicans hold a 53-47 majority in the Senate, giving an automatic edge to the Trump proposal.

But three Republicans have expressed public support for passing a clean measure to reopen the government, and other GOP senators have publicly called for Washington to pass a stopgap measure to buy time for the two sides to negotiate.

Two Democratic centrists — Sens. Joe Manchin Joseph (Joe) ManchinBiden promises Democratic senators help in battleground states Senate leaders quash talk of rank-and-file COVID-19 deal OVERNIGHT ENERGY: House Democrats tee up vote on climate-focused energy bill next week | EPA reappoints controversial leader to air quality advisory committee | Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' MORE (W.Va.) and Doug Jones (Ala.) — will also be watched closely.

Manchin on Thursday said he would vote to advance Trump's proposal. Both represent states where Trump is popular, and Jones faces a difficult reelection in 2020.

The floor drama comes a day before fallout from the shutdown will become more severe, as the roughly 800,000 federal workers either furloughed or forced to work without pay will miss their second paycheck on Friday.

Tensions are also rising after Speaker Nancy Pelosi Nancy PelosiPelosi: Ginsburg successor must uphold commitment to 'equality, opportunity and justice for all' Bipartisan praise pours in after Ginsburg's death Pelosi orders Capitol flags at half-staff to honor Ginsburg MORE’s (D-Calif.) decision to nix Trump’s request to deliver his State of the Union address next week. Trump said late Wednesday that he would wait until the shutdown is over to deliver the speech.

Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE (R-Ky.) is hoping to drive a wedge between Senate Democrats and Pelosi, who have been like peas in a pod so far.

Senate GOP leadership staff blasted out a release to reporters on Wednesday titled “Democrats Resist Pelosi.” And McConnell has been reading statements from Democratic lawmakers who sound open to making a deal on border security.

“More and more Democrats seem to be coming to the same conclusion as the rest of us. It’s time to make a deal,” McConnell said.

There have been a few signs of stress this week on the Democratic side, though the party has largely remained emboldened in the face of public opinion polls showing they are winning the shutdown fight.

An Associated Press–NORC Center for Public Affairs Research poll released Wednesday found that 60 percent blame Trump for the funding lapse. A separate CBS News poll found that 66 percent of Americans want Trump to agree to a funding bill without extra wall money and that more Americans believe Pelosi is doing a better job handling the shutdown compared to the president.

Most Democrats are expected to oppose the White House–backed funding plan, which would trade $5.7 billion on the border wall for a three-year extension of protections for Deferred Action for Childhood Arrivals (DACA) recipients and some temporary protected status holders.

But Manchin is an exception, and he said Thursday he would back the Trump-supported measure.

"I'm voting for both. I'm doing everything in my power to open up this government," Manchin said of the two proposals.

Jones, who is viewed as the most vulnerable Senate incumbent on the ballot in 2020, has not announced how he will vote. A spokeswoman for the red-state Democrat did not respond to multiple requests for comment on the issue.

Sen. Roy Blunt Roy Dean BluntCDC tells Congress it urgently needs billion for vaccine distribution On The Money: Trump undercuts GOP, calls for bigger COVID-19 relief package | Communities of color hit hardest financially by COVID-19 | Businesses, states pass on Trump payroll tax deferral Trump undercuts GOP, calls for bigger COVID-19 relief package MORE (R-Mo.), a member of GOP leadership, said Democrats need to start pitching alternatives to Trump’s proposal in order to break the stalemate.

“I think if they both fail, what the president has done is start the process of adding more to what we’re talking about, then it’s time I would hope for the president to look for even more things that he could put on the table that he’d like to do … but it’s also time for the Democrats to talk about if they don’t like the president’s DACA proposal, what to do they like? You can’t just not like everything,” Blunt said.

Democrats have been trying to build support for their own measure that would fund the parts of the government that are currently closed through Feb. 8, as well as provide billions in disaster relief funding.

“The first vote is completely partisan. The first vote is the president’s hostage-taking position codified into an amendment,” Schumer said. “The second vote is the opposite. ... If President Trump weren’t opposed to it, there would be nothing controversial about the second vote and just about every Republican would vote for it as they did the first time a month ago.”

Though the Senate previously passed a continuing resolution late last year, the political calculus changed dramatically for Republicans when Trump came out against the measure. Republicans — who are defending a majority of their 2020 Senate seats in red states — don’t want to set up a fight with Trump over an issue viewed as crucial to their base.

Democrats hope that because the Senate is voting first on the president’s proposal, more Republicans will vote for the stopgap bill after the White House-backed measure goes down.

So far three GOP senators — Sens. Lisa Murkowski Lisa Ann MurkowskiSenate Republicans face tough decision on replacing Ginsburg What Senate Republicans have said about election-year Supreme Court vacancies McConnell says Trump nominee to replace Ginsburg will get Senate vote MORE (R-Alaska), Susan Collins Susan Margaret CollinsSenate Republicans face tough decision on replacing Ginsburg Democratic senator calls for eliminating filibuster, expanding Supreme Court if GOP fills vacancy What Senate Republicans have said about election-year Supreme Court vacancies MORE (R-Maine) and Corey Gardner (Colo.) — have said they will support the continuing resolution.

“I’m in the camp of being happy that we’re going to be going to the floor and having an opportunity to vote on proceeding to anything,” Murkowski said. “I’m not very optimistic at its chance of passage, but we’ve got to get ourselves off of dead center here.”

Collins and Gardner are both up for reelection in states won in 2016 by Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE. Collins's office confirmed on Wednesday evening that she would support the short-term bill as well as the president's proposal.

“The president’s put forth an offer,” Collins said. “It seems me we should get a counteroffer. That’s the way a negotiation usually works.”

Gardner's office told The Denver Post's editorial board that he would support the two measures.

Updated at 1:53 p.m.