In recent months, most of Rand Paul’s political odd-couple pairings have underscored the Kentucky senator’s Republican credentials. Paul joined with John McCain to introduce a GOP jobs bill. He teamed up with Lindsey Graham on legislation that would prioritize smaller harbors for dredging work. He worked with his fellow Kentuckian, Senate Minority Leader Mitch McConnell, on repealing net neutrality.

When Paul arrived in Washington, it was widely assumed he would spend some of his time fighting these men as well. Last week, that time finally came. On a series of votes involving foreign policy and civil liberties, one of the Senate’s most rock-ribbed Republicans channeled John F. Kennedy: “Sometimes party loyalty asks too much.”

McCain and Carl Levin, the liberal Michigan Democrat who chairs the Senate Armed Services Committee, agreed on rules for detaining suspected terrorists. They claimed it would leave most Americans untouched, affecting only a tiny minority who would take up arms against their own country as members of known terrorist organizations like al Qaeda.

Critics charged that the McCain-Levin language gave too large a role for the military in potential civilian prosecutions and lacked adequate safeguards to prevent the indefinite detention of American citizens. If the U.S. is a battlefield and the war on terror has no end in sight, it is dangerous to tell Americans, as Lindsey Graham puts it, “And when they say ‘I want my lawyer,’ you tell them, ‘Shut up.'”

Paul and McCain had a testy exchange over this amendment. “Should we err today and remove some of the most important checks on state power in the name of fighting terrorism, well then the terrorists have won,” Paul maintained. “[D]etaining American citizens without a court trial is not American.”

“Facts are stubborn things,” McCain shot back. “If the senator from Kentucky wants to have a situation prevail where people who are released go back into the fight to kill Americans, he is entitled to his opinion.”

“I don’t think it necessarily follows I am arguing for the release of prisoners,” Paul countered. “I am simply arguing that particularly American citizens should not be sent to a foreign prison without due process.”

Paul supported an amendment by Sen. Mark Udall, a Colorado Democrat, to strip the McCain-Levin detainee provisions from the national defense authorization bill. When the Udall amendment failed, Paul backed a similar measure by Democratic Sen. Dianne Feinstein of California. The Feinstein amendment was voted down by a smaller margin.

Alabama Republican Sen. Jeff Sessions then offered an amendment saying that alleged enemy combatants acquitted by civilian courts could still be held indefinitely by the military. Levin, eager to spare his fellow Democrats an awkward vote on national security, moved to pass Sessions’ amendment by unanimous consent but Paul demanded a roll call vote. “I am going to ask for the yays and nays,” Paul said.

The Sessions amendment then failed 41-59. Both Levin and McCain voted with Paul to kill it. According to some reports, Levin had been promised that Sessions’ language would be excised from the final conference report anyway. But the roll call vote defeated it outright. Later, Paul voted with a 99-1 majority in favor of a compromise purporting to clarify that existing law concerning the detention of American citizens was unchanged.

As if that wasn’t enough, Paul later pushed for a vote on revoking congressional authorization for the war in Iraq. The president had announced that the war was effectively over, so Paul reasoned that the body the Constitution authorizes to declare war should ratify that decision. Paul’s bill failed, despite a Democratic Senate majority eager to take credit for ending the Iraq war.

While only a few Republicans joined Paul’s rebellion, there were some interesting names on the list. Sens. Jim DeMint of South Carolina and Dean Heller of Nevada voted with Paul on Iraq. Sen. Mike Lee of Utah backed Paul on terror detainee rules. All three are Tea Party favorites.

Some of the Democratic votes were also revealing. Harry Reid, the Senate majority leader, once declared the Iraq war a failure. But he voted to authorize it under President Bush and has now voted against de-authorizing it under President Obama.

Sometimes Paul stood alone against both parties. Sen. Marco Rubio of Florida, a fellow Tea Party triumph from last year’s election, had bipartisan support for an amendment to bring the former Soviet republic of Georgia into NATO. “It called for the President to lead a diplomatic effort to get approval of Georgia’s Membership Action Plan during the upcoming NATO Summit in Chicago,” a Rubio spokesman explained in an email.

Paul blocked the amendment. He believed that NATO expansion in this sensitive area could embroil the United States in Georgia’s conflicts with a nuclear-armed Russia, potentially risking war.

Since Rand Paul joined the Senate, his fellow Republicans have found him much more of a team player than his father Ron Paul, the feisty libertarian-leaning congressman from Texas. Last week reminded them that Rand is still very much his father’s son.