Sen. Rand Paul — a right-wing firebrand from a deep red state — is in some ways an unlikely figure to articulate a searing case against President Donald Trump’s agenda.

But the senator from Kentucky is issuing a stark warning to fellow Republicans that Trump’s tariff policies could lead to a generational political loss for the party. And he’s raking in surprising praise from his Democratic colleagues as he pushes back relentlessly on the airwaves and the Senate floor against what he describes as Trump’s executive overreach and infringement on Congress.

In an impassioned floor speech ahead of his vote to roll back Trump’s Canada tariffs Wednesday, the senator said members of Congress had “abdicated their power” over decades, and he placed the blame on both parties.

“I am a Republican. I am a supporter of Donald Trump. But this is a bipartisan problem,” Paul said. “I don’t care if the president is a Republican or a Democrat. I don’t want to live under emergency rule. I don’t want to live where my representatives cannot speak for me and have a check and balance on power.”

As many of his colleagues are ceding Congress’ authority to Trump on the power of the purse and other issues, Paul has been an inconvenient voice pushing lawmakers to reassert themselves. He was the first GOP senator to argue that cuts made by billionaire Elon Musk’s U.S. DOGE Service needed to be codified by Congress to be legal, a tactic that the White House has now shown a willingness to pursue. And Paul is now objecting to Trump’s declaration of national emergencies to sidestep Congress and levy tariffs, even going so far as to appear on Fox News with Democratic Sen. Tim Kaine of Virginia to tout their resolution to roll back the emergency Trump declared to impose tariffs on Canada.

A libertarian and something of a lone wolf in the Senate, Paul has been raising concerns about what he sees as an overgrowth of executive authority for years.

“He and I call ourselves the Ben Franklin Caucus,” said Sen. Ron Wyden (D-Oregon), who has worked with Paul for years on legislation to limit government surveillance and restrict presidential power. It’s a reference to Franklin’s line that “Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.”

Kaine won Paul’s support during Trump’s first term for legislation to limit the president’s power to wage war in Iran, and Kaine said he drafted the resolution to undo Trump’s Canada tariffs with Paul in mind.

“Having worked on issues like this with him before, I sort of know kind of the way he likes to do them,” Kaine said. “If you go back and read the resolution, there’s no editorial opinion. It’s just a simple resolution: the emergency is terminated.”

Paul joined GOP Sens. Susan Collins (Maine), Lisa Murkowski (Alaska) and Mitch McConnell (Kentucky) in voting with Democrats to scrap the national emergency that Trump declared to levy tariffs on Canada.

Unlike those Republicans, who have been frequent Trump critics over the years, Paul has lavishly praised Trump’s Cabinet picks and his work to shrink the federal workforce. “I still think tariffs are a terrible idea, but Dios Mio, what courage, what tenacity,” Paul recently wrote on X of Trump.

Nonetheless, Paul’s decision to buck tariffs has triggered Trump’s anger. Trump blasted Paul and the other Republican senators who voted to nullify his tariffs on Canada as “unbelievably disloyal.”

“What is wrong with them, other than suffering from Trump Derangement Syndrome, commonly known as TDS?” Trump wrote in a late-night Truth Social post.

In a brief interview, Paul said a handful of Senate Republicans had told him privately that they supported his efforts even if they were unwilling to defy Trump by voting to overturn his tariffs.

“They all see the stock market and they’re all worried about it,” Paul said. “But they are putting on a stiff upper lip to try to act as if nothing’s happening and hoping it goes away.”

Seven Republican senators are backing a bipartisan bill that would scrap new tariffs after 60 days unless Congress votes to approve them. (Paul has not signed onto the bill yet and has his own legislation that would go further to reclaim Congress’s power over tariffs.) But the bill faces tough odds in Congress — and Trump could veto it even if it passes. It would take two-thirds of senators — including at least 20 Republicans — to override a veto.

Asked earlier if he had received any blowback in Kentucky for his tariff stand, Paul drily replied “only accolades” and laughed.

Paul — whose father, former congressman Ron Paul, ran for president three times and garnered a devoted following of libertarian-leaning conservatives — is used to ruffling feathers on Capitol Hill. The ophthalmologist rode into the Senate in the 2010 tea party wave, and he quickly distinguished himself with his rabble rousing on the national debt, privacy issues and objections to the intelligence community’s surveillance practices.

He has angered his fellow senators in the past by stubbornly dragging out votes late into the night to secure doomed amendment votes on his signature issues, which often force his fellow Republicans to take uncomfortable votes. But they also know that he tends to operate from strongly held beliefs.

“He’s very respectful of Donald Trump, but he’s also very respectful of his own principles,” Sen. Kevin Cramer (R-North Dakota) said, describing Paul as “the conscience of the libertarian faction of our party.”

He was among the fiercest critics of the U.S. pandemic response and Anthony S. Fauci, and said in 2021 he would not get the coronavirus vaccine because he had already been infected. Paul now chairs the Senate Committee on Homeland Security, a powerful gavel for someone who once operated more at the fringes of the conference.

Sen. Peter Welch (D-Vermont) said he called Paul on Wednesday to thank him for advocacy against tariffs.

“He is consistent — some would say stubborn,” Welch said. “But he stepped up on tariffs, and he tells it like it is.”

Welch praised Paul for standing up for Congress’s authority to levy tariffs and war, which lawmakers have eroded over many decades.

“Congressional Republicans are deferring and delegating and abdicating their responsibility to Trump,” Welch said. “So you’re concentrating power in the executive — that’s very dangerous. And I respect and admire Rand resisting that.”

Paul has made the case against tariffs to his colleagues in closed-door meetings, according to several senators, where he’s argued that tariffs are a tax that will burden Americans with higher prices. It’s a widely shared belief among Senate Republicans — although few are willing to be as vocal as Paul on it, hoping to give Trump time to make deals with individual countries to lift the penalties.

“Tariffs have also led to political decimation,” Paul told reporters recently, referencing the devastating political fallout Republicans faced after levying tariffs in 1890 and in the 1930s — after which they lost the House and Senate for most of the next 60 years. “They’re not only bad economically, they’re bad politically.”

One Republican who joined Paul in opposing the tariffs, former GOP leader McConnell, has a checkered history with his libertarian co-state senator, who often caused leadership headaches with his stubbornness. “Henry Clay would be appalled by Rand Paul,” McConnell once said of the ex-Kentucky lawmaker known as the “Great Compromiser,” according to his biography. They clashed in 2015 while McConnell was majority leader over extending a National Security Agency surveillance program that Paul had harshly criticized, despite an otherwise cordial relationship.

“We have a good personal and working relationship … Even though we don’t see eye-to-eye on everything, we certainly share our skepticism on tariffs and the impact on hardworking Kentucky families,” McConnell said in a statement about Paul.

Some of their colleagues see an irony to McConnell — who was constantly corralling GOP senators to take tough votes when he was in charge — now voting with the renegade Paul.

“Rand has consistently been independent of the team, whereas Mitch has always demanded loyalty from the team,” said Cramer, who added he felt a little betrayed by McConnell’s vote. McConnell has pointed to the likely negative effect of tariffs on his state’s bourbon and auto industries as well as the overall cost to consumers to explain his vote.

Paul, for his part, has continued to argue that his position is not about politics. “This isn’t about political party,” he said. “I voted for and supported President Trump, but I don’t support the rule of one person.”