After initially drawing praise for extracting spending concessions while averting a government shutdown, Speaker John Boehner now finds himself on the defense against conservatives who feel they were duped regarding the amount of cuts the bill would entail.

It began with a trickle. While most conservatives initially appeared satisfied with the deal Boehner struck, a few leaders, such as Rep. Mike Pence (R-Ind.), signaled early that they might oppose the deal. Pence, for example, told Fox News he would probably vote against the budget deal, but added that Speaker Boehner “got a good deal”. A few others, like Rep. Michele Bachmann of Minnesota, flatly said they would vote against it. But most conservatives seemed, at least, grudgingly supportive.

On Wednesday, however, freshman Sen. Ron Johnson (R-Wis.) issued a statement saying: “I made a commitment to support the House in its pledge to cut $100 billion from the budget … This is the first CR that does not achieve that level of spending reduction. As a result, I will vote no when this CR comes before the Senate.” The Examiner’s Mark Tapscott also added, “there is a gut feeling in some quarters today that the Boehner-Obama deal could be in bigger trouble than anybody realizes.”

Things then took a dramatic turn, though, when the AP reported that a new budget estimate “shows that the spending bill negotiated between President Barack Obama and House Speaker John Boehner would produce less than 1 percent of the $38 billion in promised savings by the end of this budget year.”

News spread like wildfire, prompting RedState’s Erick Erickson, the influential conservative blogger and TV pundit, to write, “we might really need to reconsider whether or not our existing leadership has the moral authority to continue leading.” Former Minnesota Governor Tim Pawlenty, who is exploring a run for the 2012 GOP nomination, also urged Republicans to vote against the bill on Wednesday.

But the biggest blow to Boehner probably came when the influential conservative publication National Review reversed their endorsement of the deal, writing: “The episode is strike one against the speakership of John Boehner.”

Thursday morning, The Washington Post’s Aaron Blake reported that Senator Marco Rubio of Florida would vote against the budget deal. (Rubio also talked about his decision on Thursday’s Fox & Friends, saying “This budget deal that was cut doesn’t help solve the problem.”

The House is expected to take up the budget deal today — just one day before the government would theoretically run out of money. Hotline has a running whip count of House and Senate Members who are voting against it. As of Wednesday, Speaker Boehner was still predicting the deal would pass.

To be sure, Boehner’s office is pushing back against the criticisms. They are clearly worried, as is evidenced by Boehner’s op-ed in Politico. But some conservatives are coming to his defense. Mississippi Governor Haley Barbour is defending Boehner, calling the deal “a single in the first inning”. And The Weekly Standard’s John McCormack writes, “This is all a little confusing, but the bottom line is that the conservative angst over the CR seems to be much ado about little.”

It could be a very interesting vote in the House today …

*** Correction: The quote which is now attributed to The Examiner’s Mark Tapscott was originally and mistakenly attributed to Sen. Johnson.