WASHINGTON — Congress is sending President Donald Trump a strong message of discontent with his foreign policy in a number of critical areas, a growing rebuke that increasingly includes members of Trump’s own Republican Party.

On Afghanistan and Syria, the GOP-run Senate has issued a stern warning against the president’s plans to withdraw troops. Lawmakers in the House and Senate are questioning Trump’s diplomacy with North Korea, his easing of sanctions on a Russian oligarch and even his intent to stay involved in Yemen’s civil war. And his threats to pull out of NATO are causing consternation on Capitol Hill.

The bipartisan rebuke has left the president increasingly standing alone on consequential issues of international affairs. He is seeing pushback from every corner of the ideological spectrum and across both parties.

In the latest reproach, the Senate Thursday overwhelmingly passed an amendment that disapproves of the sudden withdrawal of troops from Afghanistan and Syria. Forty-three Republicans backed the measure.

Perhaps an even more critical component of the resolution is that it was authored by Senate Majority Leader Mitch McConnell, R-Ky., who has been careful not to publicly split with the president. It was also backed by Sen. James Inhofe, R-Okla., the chairman of the Armed Services Committee, and James Risch, R-Idaho, the chairman of the Foreign Relations Committee.

Sen. John Kennedy, R-La., voted against the amendment because he said he doesn’t know if Trump is “right or wrong” on Syria.

But Kennedy minced no words when he said there is no coherent policy in the Middle East. “Our Middle East policy right now looks like something my dog’s been keeping under our back porch. Nobody knows what it is, but it’s ugly,” he told NBC News.

The newfound willingness to challenge the president on foreign policy by Republicans reflects tensions over his unconventional or seemingly impulsive decisions that simmered quietly during his first two years but were rarely voiced in public. Two years in, and following midterm elections in which dozens of Republicans lost their House seats, Trump’s party appears more willing to directly confront him on his more controversial decisions.

McConnell’s amendment, for example, is part of a larger Middle East bill that slaps new sanctions on Syrian President Bashar al-Assad’s government and shores up U.S. support for Israel and Jordan. Two Senate Republican aides say it was deliberately introduced as the first piece of legislation in the new Senate and given the designation Senate Bill 1 in a conspicuous bid to push back at Trump’s Syria withdrawal and remind the president that Congress has a role in foreign policy.

While the measure is mostly symbolic, it reflects concern among Republicans about the message that Trump’s Syria move sent to Israel and Jordan — U.S. allies and Syrian neighbors intimately affected by the decision to withdraw U.S. troops. The move essentially allowed lawmakers to go around the president to show the two countries that at least Congress has their back.

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In recent years, most mainstream Republicans have advocated an active U.S. role overseas to ensure national security at home, a world view that has at times been an awkward fit with Trump’s “America First” doctrine. Still, polls show that, by and large, most rank-and-file Republicans continue to support Trump’s foreign policy.

Thursday's action was only the latest example of a newfound willingness by Congress to insert itself in trying to issue a course correction. Lawmakers are also expressing condemnation on issues of trade, Russia, North Korea, Yemen and NATO.

In some places the president is indulging his inclination to extricate the U.S. from overseas entanglements by withdrawing troops in Afghanistan and Syria, threatening a retreat from NATO and contemplating reducing troops on the Korean Peninsula.

But in other areas he’s showing more willingness to take an active role in overseas affairs, intervening diplomatically in Venezuela and maintaining a presence in Yemen’s civil war, giving critics of all stripes space to interject.

James Carafano, foreign policy scholar at the conservative Heritage Foundation who advised the Trump presidential transition, said there are legitimate concerns about some of the president’s foreign policy pronouncements. He cited issues raised in Defense Secretary Jim Mattis’ resignation letter in December — which suggested Trump was insufficiently supportive of U.S. allies — as a critique that had resonated with many conservatives.

“The president is an unconventional statesman, we get that,” Carafano said. “Nothing in the Constitution says that he can’t be. But he does have a responsibility to make sure his administration’s policies are clear and consistently understood by our friends and enemies. And sometimes, it’s not.”

Last week the House of Representatives spoke with a near-unanimous voice, voting 357-22 to prohibit the use of funds to withdraw from NATO, something the president threatened to do during his campaign and at times throughout his presidency.

On Venezuela, there’s wide agreement on Capitol Hill among Republicans and Democrats that the president is following the lead of Sen. Marco Rubio. The Florida Republican was instrumental in the White House’s decision to back Venezuelan opposition leader Juan Guaidó over President Nicolás Maduro, according to Senate aides. And now that White House has adopted that position, Congress is attempting to ensure that there is a strategy in place to address the fallout.

At a bipartisan briefing for staff on Wednesday by the White House, State Department, Defense Department and USAID officials, Senate staff strongly pushed for answers about the humanitarian plan, security at the embassy and what a political transition in the South American country would look like, according to a Senate source.

“They are building the plane while flying it,” one Democratic Senate aide familiar with the briefing said.

Senators are also pushing for insight ahead of Trump’s upcoming meeting with North Korea President Kim Jong Un.

Sen. Cory Gardner, R-Colo., confirmed that he spoke Wednesday by phone with the U.S. special representative for North Korea, Stephen Biegun, about the upcoming summit. Gardner, who has not been pleased with the lack of information coming from the administration on North Korea, said he didn’t want to get into too many details about the call but said: “The hope is that those concrete actions will be taken in the lead-up to any summit. If there’s no concrete action, I don’t think they should meet.”

Gardner also confirmed that he and Sen. Bob Menendez, D-N.J., will reintroduce the North Korea Policy Oversight Act, which is essentially a bill to monitor the administration on North Korea talks. The 2018 version requires oral and written briefings from the White House on the negotiations, continued sanctions and “underscores the importance" that the number of U.S. forces on the peninsula are not part of the negotiations with North Korea.

As the special counsel investigation continues into potential Trump campaign collusion with Russia, Republicans have also shown increasing willingness to call out the president on policies they see as insufficiently tough on Moscow. In January, after Trump’s Treasury Department said it would ease sanctions on companies that had been controlled by Russian oligarch and Vladimir Putin ally Oleg Deripaska, 11 Republicans joined Democrats in an attempt to keep the sanctions in place. The bill failed narrowly in the Senate.

In the House, Republican and Democratic lawmakers have introduced a number of pieces of legislation to oversee the president’s foreign policy. Rep. Mike Gallagher, R-Wisc., has introduced biting bills that would financially prevent the administration from removing troops from Syria and South Korea and withdrawing from NATO.

His goal, he said, is "to remain engaged internationally so we can shape events and to maintain and build strong allies.”

“Congress needs to claw back its authority, particularly on foreign policy,” Gallagher told NBC News.

The flurry of movement comes as a coalition of senators on the left and the right has reintroduced a measure cutting off U.S. support for the Saudi-led war in Yemen despite the president’s intention to continue that support. The measure passed the Senate last year, an unexpected move that reflected growing frustration with Saudi Arabia after the murder of journalist Jamal Khashoggi at the hands of the Saudi government.

“It strikes me as the Senate reasserting its traditional role in foreign policy,” said Whit Ayres, a Republican pollster who advises numerous GOP senators. “President Trump is a nontraditional president. Some of his nontraditional positions on foreign policy diverge rather markedly from many of the senators, particularly on the Republican side.”