This week it appeared Republican Sens. Ted Cruz and Mike Lee would wage a lonely war over their threat to hold up a continuing resolution to fund the U.S. government if they are not given a vote on a budget amendment to defund Obamacare. Now, it’s not quite so lonely. Sens. Marco Rubio and James Inhofe have joined Cruz and Lee, and Senate Minority Leader Mitch McConnell said Friday that he “looks forward to supporting” the amendment.

It’s a significant step forward for Cruz and Lee. But the Senate Republican caucus remains deeply divided about defunding Obamacare. Sources say that at a Republican caucus lunch a few days ago, several GOP senators expressed opposition to Cruz and Lee’s proposal. And of course, the 55-member Democratic majority will not give it the time of day. But Cruz and Lee are determined to keep up opposition to Obamacare, even though it has flagged in some other quarters of the Republican Party.

And in Rubio, the two have an ally sure to bring a higher profile to the cause. The continuing resolution fight is “a perfect opportunity for us to have a debate once again on Obamacare,” Rubio told radio host Hugh Hewitt Friday. “I don’t think there’s been enough attention paid to it. It’s been awhile, we’ve moved onto these other issues, but there is, right now out there, probably nothing more damaging to our economy in the short term than this implementation of Obamacare.”

Saying “I don’t think anyone is in favor of shutting down the government,” Rubio said he nonetheless has vowed not to vote for another continuing resolution to put off dealing with budget problems. The only way he would vote for one, he told Hewitt, would be if the continuing resolution contained a measure defunding Obamacare. In that case, Rubio said, “I will vote for a continuing resolution, even if it’s temporary, because it does something permanent, and that is defund this health care bill, this Obamacare bill that is going to be an absolute disaster for the American economy.”

Given the Democratic majority in the Senate, not to mention Republican divisions on the issue, defunding Obamacare remains an impossibility. But there is a sense that what Cruz started (with Lee joining in almost immediately), is gathering momentum. There was no better sign than the statement released by McConnell on Friday. “Obamacare is a costly mistake that we cannot afford and my preference would be to repeal it, root and branch,” the Minority Leader said. “We are going to have a number of spending and budget bills in the coming weeks. I know Ted Cruz is planning to offer an amendment to defund Obamacare and I look forward to supporting him.”