Sen. John McCain (R-Ariz.) has repeatedly come under attack from President Trump. Here are just a few of their rocky moments. (Peter Stevenson/The Washington Post)

After Sen. John McCain (R-Ariz.) won his primary, it took him precisely one day to ditch Donald Trump. McCain campaigned for reelection on the premise that Hillary Clinton would win and that he could be a check on the White House.

Trump's win does not seem to have changed McCain's plan all that much.

A week into the new administration, McCain has opposed him on enough issues to equate to nearly a criticism a day of the new president's proposals, including on free trade, torture and his budget priorities.

McCain can't stop Trump on his own — but he can sure make the president's path to success on Capitol Hill a lot bumpier.

The Republican Party's 2008 presidential nominee is now one of the Senate's most senior members. He chairs the Senate Armed Services Committee, which sits at the intersection of many of Trump's foreign policy proposals. And many issues, he has opposed the president's positions.

Such as:

On renegotiating NAFTA, McCain says, “Facts are stubborn things”

On Wednesday, Trump suggested that he might follow through on one of his campaign promises to renegotiate the North American Free Trade Agreement. To that, McCain replied, via a statement:

“Facts are stubborn things, and the facts clearly show that NAFTA has delivered enormous economic benefits to the citizens of my home state since it went into effect in 1994. In just two decades, Arizona’s exports to Canada and Mexico have increased by $5.7 billion, or 236 percent.”

On withdrawing from the TPP: It's “a serious mistake”

On his fourth day in office, President Trump signed an executive order formally withdrawing the U.S. from the Trans-Pacific Partnership trade deal. Crafted by the Obama administration, the trade deal failed to be ratified by Congress during Obama's two terms. (Daron Taylor/The Washington Post)

This week, Trump put the final nail on the coffin of President Barack Obama's signature trade deal with countries along the Pacific Rim. (It was already basically dead in Congress as public opinion has turned against free-trade deals.)

In a statement, McCain said that ending U.S. involvement in the Trans-Pacific Partnership is “a serious mistake” and “the wrong decision.” And he warned that it would give China — which was not part of the trade deal — more leverage in the Asia-Pacific region, an analysis many foreign policy experts agree with:

“This decision will forfeit the opportunity to promote American exports, reduce trade barriers, open new markets, and protect American invention and innovation. It will create an opening for China to rewrite the economic rules of the road at the expense of American workers. And it will send a troubling signal of American disengagement in the Asia-Pacific region at a time we can least afford it.”

On bringing back waterboarding: “The law is the law”

A draft executive order awaiting Trump's signature would order a policy review of secret CIA prisons, known as black sites, and consider restarting practices such as waterboarding, which Congress outlawed — with a heavy lift by McCain himself — under criticism that it amounted to torture.

McCain's responding statement was the equivalent of “when hell freezes over”: “The President can sign whatever executive orders he likes. But the law is the law. We are not bringing back torture in the United States of America.”

(One thing Trump has done that McCain approves of: Pick a defense secretary and heads of the CIA and Department of Homeland Security who have all said they have no intention of reinstating torture.)

On picking a fiscal conservative for his top budget post: McCain is offended


Don't let smiles deceive you: Sen. John McCain (R-Ariz.) tore into Rep. Mick Mulvaney (R-S.C.) to lead the Office of Management and Budget. (Chip Somodevilla/Getty Images)

Trump, who has favored big-spending policies more in line with Democrats, surprised many when he plucked one of the most outspoken fiscally conservative members of Congress, Rep. Mick Mulvaney (R-S.C.), to lead the Office of Management and Budget.

McCain does not like Mulvaney for another reason — the tea partyer has frequently voted against raising the budget for military spending. McCain lashed out at Mulvaney in a Senate hearing Tuesday for that: “All I can say to you, sir, is I’m deeply concerned about your lack of support for the military.”

When Mulvaney could not recall some of his votes to reduce defense spending, McCain fired: “I tell you, I would remember if I voted to cut our defense the way you did. Maybe you don’t take it with the seriousness that it deserves.”

For now, it seems as if Trump agrees with McCain that military spending should come before budget prosperity: He told Fox News's Sean Hannity on Thursday a balanced budget is no longer a priority.

On Trump's pick for secretary of state: McCain will support — with hesitation


McCain and Sen. Marco Rubio (R-Fla.) in the Senate in November, two critics of Rex Tillerson. (Alex Brandon/AP)

McCain was one of the first senators of any party to express concern about Trump's pick to be secretary of state, Rex Tillerson, because Tillerson's economic ties to Russia while he was chief executive of ExxonMobil. “There's also a realistic scenario that pigs fly,” McCain retorted when asked by the Houston Chronicle whether he would support him.

He eventually decided to get onboard but with hesitations. Here's what McCain, along with Sen. Lindsey O. Graham (R-S.C.) — another Trump antagonist in the GOP — said in a joint statement Sunday:

“We have decided to support his nomination to be Secretary of State. Though we still have concerns about his past dealings with the Russian government and President Vladimir Putin, we believe that Mr. Tillerson can be an effective advocate for U.S. interests.”

On Russia: McCain wants to get tough

Sen. Lindsey Graham (R-S.C.) called for tougher sanctions on Moscow and Sen. John McCain (R-Ariz.) called Russian President Vladimir Putin a "thug and a murderer." (Reuters)

Trump's tendency to give Russia the benefit of the doubt about whether it meddled in the U.S. election stands in stark contrast to McCain's judgment. He has said what Russia did amounts to “an act of war” and held a hearing on cybercrimes related to Russia.

Trump has since acknowledged Russia hacked into Democratic Party emails, but one of the biggest potential flash points between McCain and Trump could be yet to come. Trump has signaled he would consider a deal with Putin to relax some sanctions; McCain (along with other top Senate leaders) said he will introduce a bill that prevents Trump from lifting sanctions.

“I hope President Trump will put an end to this speculation and reject such a reckless course,” McCain said in a statement Friday, ahead of an expected phone call between Trump and Putin.