Senate Majority Leader Mitch McConnell appears increasingly unlikely to have the votes necessary to pass a short-term patch to fund the government past Friday should the House advance the measure Thursday evening.

At least three GOP senators will vote against a continuing resolution to keep the government funded past Jan. 19, as Republican congressional leaders struggle to find the votes in either chamber to advance it. They will join a large chunk of Democrats who also say they will oppose the CR.

“There are going to be some people on both sides of the aisle who won’t support it. But if Chuck Schumer instructs all Democrats to vote no then the government is shutting down,” Senate Majority Whip John Cornyn of Texas said.

Sens. Mike Rounds of South Dakota, Lindsey Graham of South Carolina and Rand Paul of Kentucky all intend to vote against the CR in its current form. Rounds expressed frustration over the continued reliance on temporary funding measures, while Graham continues to push for a vote on his proposal to address the pending expiration of the Deferred Action for Childhood Arrivals program.

Rounds and Graham voted for the last CR in December. Other Republican members who routinely vote against short-term funding bills, such as Sen. Mike Lee could also vote against the House bill.

A Republican lawmaker speaking on background to discuss internal conversations said the conference’s Wednesday policy lunch grew heated at times as multiple senators voiced frustration over the need for yet another short-term patch.

Watch: Clock’s Ticking on Deal to Dodge a Government Shutdown

“I certainly am going to take up what the House sends us.,” Senate Majority Leader Mitch McConnell told reporters after that lunch. “I believe we have a good chance of passing it.”

A large bloc of Senate Democrats are also expected to vote against the CR over demands that the chamber first address DACA, which covers immigrants who come to the country as children. Even some members who voted for the last short-term extension in December, like Sen. Angus King, an independent from Maine who caucuses with Democrats, have announced they will vote against this CR.

Democratic Sens. Mark Warner and Tim Kaine, both of Virginia, announced Thursday they will also vote against the measure. Their objection is noteworthy given the large amount of federal employees in their state.

Senate Minority Leader Charles E. Schumer, during his opening remarks, suggested the CR is doomed to fail in the chamber.

“The House Republican Majority is moving forward with a continuing resolution that is likely to be unacceptable to the Senate, and may well be unacceptable to House Republicans,” the New York Democrat said.

GOP leaders have said the four-week patch is needed to allow discussions on both immigration and fiscal year 2018 spending levels to continue. Republicans argue a government shutdown would only hinder those talks.

“If the Democrats shut down the government over DACA, it would almost certainly poison the ongoing negotiations,” a Senate GOP aide said.

Republican leaders are said to have a very slim margin for success, so any GOP defections are noteworthy. The measure will need 60 votes in the Senate to pass, and Republicans hold only 51 seats.

A spokesman for Senate Majority Whip John Cornyn of Texas declined to comment on the current vote count.

House Speaker Paul D. Ryan and his leadership team remain short of the votes needed to pass a proposed four-week CR, but hope to muster the support necessary to advance the measure on Thursday.

House Minority Leader Nancy Pelosi urged her members to vote against the measure, which also includes a repeal of several taxes included in the 2010 health law and a six-year extension of a popular children’s health insurance program.

McConnell said the inclusion of those measures makes it an “attractive package” for Democrats.

Some Republican senators have voiced support for an even shorter CR to force Congress to stay in Washington D.C. and address lingering issues like a long-term spending bill and immigration.

“I become more pessimistic about that overtime,” Sen. Jerry Moran, R-Kan., told CNBC when asked whether he thinks the government will stay open. “We ought to have a continuing resolution, not shut down government. But we ought to do it for a very short period of a time, a day or two, and stay here and resolve these differences.”