Assuming Ted Cruz can get the votes, a 2014 continuing resolution that would avoid a government shutdown could face a filibuster by the freshman Texas Republican, who is vehemently opposing any significant changes to the stopgap funding measure the House recently sent to the Senate.

The House resolution appropriates $986 billion to fund the entire government except the Affordable Care Act, or Obamacare. The Senate is currently debating the measure and a series of procedural votes are expected to occur this week before a majority vote is taken to strip the law of the Obamacare-defunding language.

Senate Democrats have said that any bill that defunds Obamacare, which Republicans have tried to do 42 times, is dead in their chamber, where they have the majority. 

Cruz has been trying to rally fellow Senate Republicans to vote against cloture to end the debate on the resolution and is requiring a 60-vote threshold for amendments to the House bill. But Cruz stands almost alone.

While the freshman senator has the backing of figures like Sens. Mike Lee of Utah and Marco Rubio of Florida, other Republicans have left Cruz entirely on his own on the issue. Here are some of the colleagues the Cruz-Lee-Rubio team has lost:

Senate Minority Leader Mitch McConnell of Kentucky

Count him out. McConnell wants to keep the government open and has been urging Democrats to join the defunding effort. What he will not do, however, is prevent a bill that takes money from the health care law from proceeding. The minority leader’s reasoning is that once cloture is invoked, the spotlight will be on Democrats voting to amend the continuing resolution.

“If five Senate Democrats vote against the majority leader, Obamacare will be defunded,” McConnell said. “That’s a vote we should want to have. ... This is a rare opportunity to defund this law with a simple majority. We should have that vote. I just don’t happen to think filibustering a bill that defunds Obamacare is the best route to defunding Obamacare. All it does is shut down the government and keep Obamacare funded. And none of us want that.”

Minority Whip John Cornyn of Texas

It's not just the Senate Republicans' leader who has distanced himself from Cruz. The whip is steering clear of his fellow Texan too. 

“Senator Cornyn will support the House bill that defunds Obamacare,” Cornyn’s spokeswoman Megan Mitchell told the Washington Post. “He will not block a bill that defunds Obamacare.”

John McCain of Arizona

The senator and 2008 presidential nominee told Politico that Republicans can better maximize their strategy by going through the amendment process. “In my view, a better strategy would be to try to get amendments up that force tough votes,” McCain said.