Conservatives in the U.S. Senate are gearing up to challenge Republican leadership today, setting their sights on a plan to repeal Obamacare with 51 votes — a measure that would easily pass if the 54 GOP senators support it.

The move comes after several contentious days of fighting over the GOP leadership’s priorities. Senate Majority Leader Mitch McConnell, R-Ky., allowed a vote Sunday to reauthorize the Export-Import Bank despite his stated opposition. It passed, 67-26, but drew a sharp rebuke from conservatives.

“The American people elected a Republican majority believing that a Republican majority would be somehow different from a Democratic majority in the United States Senate,” Sen. Ted Cruz, R-Texas, said. “Unfortunately, the way the current Senate operates, there is one party, the Washington party.”

Cruz accused McConnell of lying in a fiery floor speech Friday, then Sunday linked him with Senate Minority Leader Harry Reid, D-Nev., for denying conservatives the opportunity to vote on amendments to defund Planned Parenthood and require Iran to recognize Israel’s right to exist.

“To the millions of Americans who rallied in November believing if only we got a Republican majority in the Senate something would be different,” Cruz added, “this was a clarifying and a sad moment.”

Despite the setback Sunday, conservatives are vowing to press their case again Monday.

Repealing Obamacare With 51 Votes

Sen. Mike Lee, R-Utah, announced he would push for a vote to repeal Obamacare with a 51-vote threshold.

The Senate voted 49-43 Sunday to defeat an amendment to repeal Obamacare. Because it required 60 votes, Republicans were unable to overcome the hurdle. The 49 votes in favor of the plan were all Republicans; five GOP senators didn’t vote.

“Republicans will have the opportunity resurrect that Obamacare amendment later on in the process,” Lee said, “and put it back before the Senate in a manner that only requires a simple-majority vote.”

Lee plans to do exactly that today using Senate rules to force a vote that requires a simple majority. Lee believes his amendment should be ruled “germane” and require 51 votes because, even though the Senate is debating a highway bill, the underlying legislation is H.R. 22, which would partially repeal Obamacare.

Republicans signaled Sunday they might not go along with the plan. That would stymie Lee, who needs 51 of his GOP colleagues to support the move.

Lee and Cruz couldn’t even get close to that Sunday on their Planned Parenthood and Iran amendments. Both were denied a roll-call vote, a maneuver Senate experts said was highly unusual.

Cruz called it an “unprecedented” plot by McConnell and Reid.

“What we just saw a moment ago is unprecedented in the annals of Senate history,” Cruz said. “It consisted of the majority leader and the minority leader denying members the ability to have votes on their amendments and indeed the ability even to have a roll call vote.”

Lee is expected to make his appeal on the Obamacare amendment Monday night.

A Rare Sunday Session

In a statement, McConnell maintained that his primary focus is forcing the Senate to act quickly on a highway funding bill this week. “Time is running short to complete our work,” he told his colleagues. The Highway Trust Fund’s authorization will expire July 31.

The rare Sunday votes were the beginning of a process that will play out this week. The so-called “must-pass” highway bill gives McConnell an opportunity to fulfill a promise GOP leaders made to supporters of the Export-Import Bank. In exchange for their votes on President Obama’s trade bill May 21, Ex-Im’s proponents cut a deal to add an amendment to the highway bill.

Even though more Republicans voted against Ex-Im (by a margin of 26 to 23), the measure easily passed Sunday with unanimous Democrat support.

The Debate Over the Export-Import Bank, Explained in 90 Seconds

Ex-Im is a little-known government agency that provides taxpayer-backed loans foreign countries and companies so that they may purchase U.S. products. Supporters argue that Ex-Im helps small businesses compete in a global market. Opponents say the bank is an example of corporate welfare and cronyism. The agency’s charter expired on June 30.

Prior to the vote on Ex-Im, the Senate rejected the amendment repeal Obamacare.

McConnell argued that only allowing two amendments was the most efficient and fair solution.

“Amendment votes are hardly a rarity here anymore. We will have more opportunities soon to address other issues in the weeks and months ahead, and I will work with colleagues to help ensure that votes on other priorities occur,” McConnell said.

Cruz’s Iran amendment would’ve kept economic sanctions on the Iranian regime until its leaders “acknowledge Israel’s right to exist” and the country releases four American hostages.

Lee introduced an amendment to defund Planned Parenthood in light of recently released undercover videos showing two of the organization’s executives discussing the sale of fetal organs, a felony in the United States.

McConnell’s Allies Criticize Cruz

On Friday, Cruz took to the Senate floor to accuse McConnell of lying to him and orchestrating a backroom deal with Democrats.

McConnell’s allies rallied to his defense over the weekend as Cruz was rebuked by several of his Republican colleagues, including fellow Texas Sen. John Cornyn.

According to Politico, Cornyn said that Cruz’s amendment was a “terrible mistake.”

“If the rule that the junior senator from Texas is arguing for is embraced, we will lose all control of the Senate schedule. There will be chaos,” Cornyn said. “Any senator who wants to get a vote on an amendment will be entitled to do so and that can’t be the rule. It’s not the rule. It’s never been the rule.”

Sen. Orrin Hatch, R-Utah, the longest-serving Republican, defended McConnell in comments that appeared to be directed at Cruz.

“In recent times the Senate floor has too often become a forum for partisan messaging and ideological grandstanding rather than a setting for serious debate,” Hatch said. “It has been misused as a tool to advance personal ambitions, a venue to promote political campaigns, and even a vehicle to enhance fundraising efforts — all at the expense of the proper functioning of this body.”

Hatch, who called for “comity and respect,” did not respond to The Daily Signal’s questions about the Senate’s refusal to allow votes on Cruz and Lee’s amendments Sunday.