Sens. Ted Cruz and Mike Lee are challenging leaders over amendments to the highway bill. (Photo by Alex Wong/Getty Images)

Conservative Sen. Mike Lee abandoned plans late Monday night to demand a controversial vote on repealing Obamacare following a meeting in which he apologized to Senate Majority Leader Mitch McConnell for the actions of a Lee staffer.

Lee gave up his plan to seek an amendment to the must-pass highway bill with a simple-majority vote — a tactic known as the “nuclear option” — after serious backlash from Republican colleagues, including McConnell.

Republicans were angered by an e-mail sent by a Lee staffer to outside groups, including the conservative Heritage Foundation and the Cato Institute, encouraging them to “score” the amendment vote. That would have forced Lee’s colleagues to support his Obamacare gambit or risk criticism from the right.

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Lee’s actions prompted McConnell to call an hour-long closed-door meeting Monday night to bring the party together on a central strategy after weeks of infighting. Lee at first proposed pulling the amendment in favor of getting a later vote during budget reconciliation.

Lee Communications Director Conn Carroll said the senator spoke to McConnell ahead of the Monday night meeting and apologized for the e-mail from his staffer and said that the staffer was reprimanded.

Republicans halted a similar procedural move from Sen. Ted Cruz (R-Tex.), when he tried on Sunday to stop the Iran nuclear deal until that country recognizes Israel and frees American hostages.

The Cruz and Lee efforts highlighted tension within Senate GOP ranks over when they should pick fights with the Obama administration and when they should hold their fire and move bipartisan legislation. Only a small handful of Republicans rose on Sunday to support Cruz.

[House won’t vote on Senate highway bill, putting trust fund at risk]

Lee and McConnell have had a bumpy relationship from the start, and the move to ditch the rules is just their latest conflict. Lee joined a group of conservative senators in a push to ban earmarks in 2010, just weeks after he was elected, putting him at odds with McConnell’s pro-earmark position from day one.

They have since repaired their relationship and Lee now serves as an appointed member of McConnell’s leadership team. Lee’s spokesman, Conn Carroll, said the senator plans to keep his position in leadership and that the dust-up over rules is nothing more than a political disagreement.

Democrats famously used the so-called nuclear option in 2013 to break a blockade of presidential nominees by allowing them to be confirmed with simple-majority votes, leading to angry protests from Republicans who said they were ditching Senate traditions in the name of partisan politics.

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But Sen. John McCain (R-Ariz.) told reporters ahead of the Cruz vote that there was no reason for Republicans to use the Democrats’ 2013 move as a justification for employing a similar tactic now.

“I think if we’re going to change the rules we’d better have debate and we’d better have votes and we’d better have consultation,” McCain. “We can’t just turn around and change the rules of the Senate.”

On Monday night, Lee was going to offer the Obamacare repeal amendment that failed through normal procedure on Sunday. He intended to argue that his proposal is directly related to the highway funding bill and appeal the ruling of the chair that it is not. Under Senate rules, amendments that are directly related, or germane, to the underlying legislation can pass with just 51 votes.

Lee would need at least 11 vote to even get to a vote on overturning the chair’s ruling. But he was expected to fall far short of even that threshold because his parliamentary gambit is opposed by most Senate Republicans.

Senate Majority Whip John Cornyn (R-Tex.) on Sunday said there’s no reason to change Senate rules because legislation that has sufficient support will ultimately pass.

“Any time 65 senators want to do something here in the Senate, sooner or later they’re going to get their way,” he said on the Senate floor.