WASHINGTON — They have issued concerned news releases and sent solemn tweets. But when it came time to stand up to President Trump on tariffs this week, Senate Republicans took a pass, casting aside the party’s long-held commitment to free trade for fear of poking the bear.
At least that is how Senator Bob Corker interpreted the outcome of the intraparty fight over how to combat Mr. Trump’s protectionist policies.
“Gosh, we might poke the bear,” Mr. Corker, a Tennessee Republican who is retiring, said with fake outrage as he laced into his colleagues for disavowing their beliefs on trade because they are scared of the president and the prospect of losing power.
The decision by Republican leaders this week to block a vote on Mr. Corker’s amendment to an annual defense policy bill that would have required the president to get congressional approval to impose tariffs on national security grounds was something of a watershed. Republican leaders maintained that the measure would have created procedural issues that could jeopardize the underlying defense policy bill. They privately called Mr. Corker’s reaction hyperbolic, and other Republicans said they would continue to make their differences with the president clear.
But the amendment’s defeat, without a vote tallied, was a setback for a core Republican principle, and it played out in public on the Senate floor, underscoring just how far most congressional Republicans would go to avoid confronting Mr. Trump ahead of the November midterm elections. The increasingly lonely forces of opposition within the party are coming from those who are leaving politics or those in the chattering classes safely removed from a Republican electorate overwhelmingly aligned with the president.
“There’s no question that leadership in general is wary of doing anything that might upset the president,” Mr. Corker said on Wednesday, describing his party’s following of Mr. Trump as “cultish.”
Other Republicans were equally deflated on Wednesday, but the path forward was not clear. Senator Mitch McConnell of Kentucky, the majority leader, is reluctant to put forward legislation that Mr. Trump does not support because he does not want to waste time making Republican senators take difficult votes ahead of a possible veto.
“It’s terribly disappointing,” said Senator Patrick J. Toomey, Republican of Pennsylvania, who helped write the Corker trade amendment. He added: “We are the Senate. We’re not potted plants. We should be doing what we think is right.”
Douglas Holtz-Eakin, the former director of the Congressional Budget Office and president of the conservative American Action Forum, said the Republican trade rebellion collapsed because the party is genuinely divided on the issue these days — and laying bare those divisions would not help Republican election prospects. The fear of a seething presidential tweet has left some in the party paralyzed.
“They’re going to have to pick a place to make a stand, and they haven’t,” Mr. Holtz-Eakin said.
One area where many Republicans are continuing to hold strong against Mr. Trump is national security. While they have buckled on trade, the next test will be whether Republicans will dare Mr. Trump to veto the defense policy bill over ZTE, the Chinese telecommunications company.
Senate Republicans have included in the defense measure an amendment that would restore harsh penalties on ZTE for violating American sanctions that the Trump administration has moved to lift. If it makes it to the president’s desk, the provision would undercut the settlement that the Commerce Department reached with the company this month that essentially threw it a lifeline at the request of China’s president, Xi Jinping.
The White House on Wednesday signaled that it would try to strip that amendment out when House and Senate negotiators hash out a final National Defense Authorization Act.
“The administration will work with Congress to ensure the final N.D.A.A. conference report respects the separation of powers,” Hogan Gidley, a White House spokesman, said, insisting that the new agreement makes ZTE pay for its violations and gives the government sufficient oversight of the company to protect the United States.
Senator Marco Rubio, Republican of Florida, who has been a vocal advocate of the Senate’s approach, said the White House was entitled to its opinion, but he stood firm.
“ZTE poses a significant national security threat to U.S. telecommunications, and we shouldn’t be doing anything that allows them to stay in business,” Mr. Rubio said.
Consternation over ZTE has created bipartisan backlash against Mr. Trump, and lawmakers have been more willing to defy him on national security issues than trade disputes.
“ZTE combines two potent issues: economic security with China plus national security,” said Senator Chuck Schumer of New York, the Democratic leader. “Both China trade policy and national security have broad and deep support in both parties.”
Trump administration officials have argued that the president is using the threat of tariffs and showing flexibility over ZTE as part of a broader strategy to overhaul America’s trade deals, reorient commerce with China and strike a peace agreement with North Korea. His Republican allies in Congress contend that he should have the space to maneuver.
“I’m tired of senators trying to undercut President Trump at every turn, especially in the middle of a negotiating process,” Senator David Perdue, a conservative Georgian and ally of Mr. Trump, said on the Senate floor on Wednesday.
He moved on Wednesday afternoon to strip the ZTE provision from the defense bill, only to be blocked.
While Republicans appear ready to swallow their worries about trade for the moment, an all-out trade war could restore their spines. Breaking with the president has its risks, but rattled financial markets and slower economic growth are also problematic in an election year.
Mr. Trump could roll out more tariffs on China as soon as this week, and countries are preparing to hit back with tariffs of their own on American products, from Kentucky bourbon to Harley-Davidsons.
Next Wednesday, Senator Orrin G. Hatch, Republican of Utah and chairman of the Finance Committee, will hold a hearing on the tariffs and question Wilbur Ross, the commerce secretary, about their potential harm to American consumers.
After a meeting at the Capitol with the Senate Foreign Relations Committee on Wednesday, Chrystia Freeland, Canada’s foreign minister, warned that her country had retaliatory tariffs ready to be unleashed on July 1. She said that Canada was rolling them out more in sorrow than in anger and that she hoped retaliation could be avoided.
“The answer is very simple: The United States has to remove these unfair illegal tariffs from Canada,” Ms. Freeland said.