Sen. Rand Paul, R-Ky., has a secret weapon in his war on the Republican establishment. The weapon's name is Donald Trump.

Paul ended the week by saying he had spoken with Trump and he agreed with the Kentucky Republican about repealing and replacing Obamacare simultaneously.

Trump said as much in his post-election interview with "60 Minutes." Leslie Stahl asked Trump about the "millions of people" who could lose their health insurance coverage during the gap between Obamacare being repealed and replaced.

"No, we're going to do it simultaneously," Trump replied. "It'll be just fine. We're not going to have, like a two-day period and we're not going to have a two-year period where there's nothing. It will be repealed and replaced."

Some Republicans in Congress have other ideas. It is not uncommon for a lawmaker to appeal to the authority of a president of his own party. Common cause between Paul and Trump seemed unlikely, however.

Paul is a leader of the libertarian wing of the GOP. Trump is viewed as a big-government Republican on entitlement spending, infrastructure spending, civil liberties and trade. The two have a history of clashing when they were both seeking the Republican presidential nomination. Paul ran a youth-oriented campaign and exhorted Republicans to practice minority outreach. Trump did not.

Yet Obamacare was not the first time the Tea Party senator has invoked Trump. Paul will have his disagreements with Trump and has already come out strongly against some of the more hawkish Republicans the incoming administration has been considering for national security positions, such as John Bolton and Rudy Giuliani.

Less remarked upon is the authority figure Paul has cited against "unrepentant supporters of the Iraq war" like Bolton: President-elect Trump.

"What I've said all along is that I agree with Donald Trump that nation-building hasn't made us safer," Paul said in a television interview. "It's been very expensive and hasn't worked. Regime change hasn't worked in the Middle East. The Iraq war was a strategic failure."

"I want someone to be at secretary of state who agrees with Donald Trump on those key issues because this is an ongoing process where people are still advocating for toppling the Assad regime as if regime change will make things better there," Paul continued.

This is a shift from the primaries, when Paul likely saw Trump taking a limited number of antiwar Republican votes that rightly belonged to him. Paul's 2016 campaign ended after Iowa, where Trump won 9 of the counties that had gone for the senator's father in 2012 while Ted Cruz won five.

Trump called the Iraq war a "big, fat mistake" and Cruz actively worked to win over libertarian-leaning Republicans who had supported Ron Paul for president in 2008 and 2012. The elder Paul voted against the Iraq war and was its only opponent among the major Republican candidates during his two GOP presidential campaigns.

"Donald Trump is a delusional narcissist and an orange-faced windbag," the younger Paul said on Comedy Central in January 2016. "A speck of dirt is way more qualified to be president."

What changed? Rand Paul endorsed Trump for president after he won the nomination, despite the Libertarian Party having a relatively strong nominee in former New Mexico Gov. Gary Johnson (his father endorsed neither candidate).

Trump is popular in Kentucky and Democratic nominee Hillary Clinton was viewed as an existential threat to the state's coal jobs. While Paul won re-election easily, beating Lexington Mayor Jim Gray by nearly 15 points, Trump ran a few points ahead, trouncing Clinton by 30 points.

Attacking Trump didn't work any Republican who tried it in 2016, as evidenced by former Massachusetts Gov. Mitt Romney and former Texas Gov. Rick Perry having to engineer even bigger reversals on the president-elect.

"It's much easier once you understand what Trump is," a libertarian-leaning Republican said of dealing with the Trump phenomenon. "President is pretty definitive."

For his part, Trump had expressed admiration for Paul before the senator started criticizing him. The two played golf together in 2014.

Many of the younger liberty Republican activists who entered GOP politics to support the Pauls oppose Trump passionately. But that has proved less true of the voters potentially available to such candidates in Republican primaries and even older generations of Paul-aligned libertarians.

Lew Rockwell's website, for example, has been on balance pro-Trump. Walter Block, a radical libertarian economist who has backed both Pauls, supported Trump. So did Justin Raimondo of Antiwar.com.

Paul isn't likely to align himself anywhere nearly as closely with Trump. Libertarian resistance to the new president is expected in Congress, with Paul one of the Republicans taking the lead. Trump's attorney general nominee Jeff Sessions, to cite just one area of potential conflict, is diametrically opposed to Paul on national surveillance, civil asset forfeiture, state-level marijuana legalization and criminal justice reform.

A better example might be Paul ally Rep. Thomas Massie, R-Ky. Massie endorsed Trump for president and told the Washington Examiner's Tim Carney he was "better than 90 percent of the congressmen I serve with." But Massie has also argued Trump wasn't elected king and exhorted fellow lawmakers to retake their constitutional powers from the executive branch.

Trump may not be the only Republican in Washington using both carrots and sticks.