Republicans in Congress are giving President Trump the cold shoulder as he pushes them into another risky political battle to replace Obamacare, insisting they won't act until the White House delivers a detailed proposal.

The Trump administration is pursuing a federal lawsuit that could invalidate the Affordable Care Act signed by former President Barack Obama nine years ago, removing popular coverage protections for Americans with pre-existing medical conditions. Fearing a voter backlash, Republicans who for years championed repealing the law are balking at the president’s latest attempt to fulfill a 2016 campaign promise, believing the window for success has closed.

The GOP would much prefer to keep the spotlight on Democratic plans to abolish private insurance and put healthcare under government control.

Roy Blunt of Missouri, the fourth-ranking Senate Republican and the party’s chief policymaker, said there have been no internal discussions on healthcare and emphasized there are no plans to develop alternatives to Obamacare absent clear direction from Trump. “We’ll be eager to see the president’s proposal,” Blunt, chairman of the Senate Republican Policy Committee, said Wednesday.

“I’m anxious to see what the White House is going to recommend in terms of a healthcare delivery system that looks like somebody designed the damn thing on purpose,” added Sen. John Kennedy, R-La. Asked if Trump or his deputies have assured Republicans that the administration will provide congressional Republicans with a blueprint, Kennedy conceded they have not. “I’m assuming they will.”

Special counsel Robert Mueller this week gave Trump a clean bill of political health ahead of 2020, concluding the president didn’t collude with Russia to defeat Democrat Hillary Clinton 2016. On Capitol Hill, Republicans celebrated, amplifying the White House message that the federal probe was a waste of time driven by bitter partisans on the Left and in the media on social media platforms like Twitter and Facebook.

[Related: Trump hands Democrats their 2020 healthcare attack strategy]

But after Trump tweeted that the Republican Party is the "party of health care," in the wake of the administration’s surprise move to try and get rid of Obamacare? Crickets. Not one Republican leader in Congress since had retweeted that post, let alone adopted the messaging.

Sen. Todd Young of Indiana, chairman of the National Republican Senatorial Committee, the Senate GOP campaign arm, declined to endorse Trump's move, choosing instead to underscore the party's support for key elements of Obamacare. “One thing’s for sure, we all want the American people to understand that every single Republican wants to ensure that pre-existing conditions are protected, so that’s foundational,” he said.

Republicans are still scarred by the drubbing they experienced in the midterm elections. Last year, Democrats, after years of losing seats because of Obamacare, turned the tables and picked off GOP-held districts on the strength of a message that accused Republicans of opposing a host of popular coverage protections because they supporting partially repealing the Affordable Care Act.

In floor remarks Wednesday morning, Senate Majority Leader Mitch McConnell, R-Ky., did his best to steer the debate back toward Democrats' "Medicare for All" push, making no mention of Trump’s latest push to do away with the Affordable Care Act.

[Also read: Trump promises healthcare plan 'far better than Obamacare']

“Democrats are pushing a ‘Medicare for None’ scheme that would make it unlawful to provide the private health insurance policies that American families rely on and force everyone into a brand new government scheme designed here in D.C.,” McConnell said.

Privately, Republicans are far more frustrated with Trump than they are admitting.

With a favorable end to the Mueller investigation, the president and his party were enjoying a positive news cycle, as Democrats and other critics reckoned with losing a major advantage in the 2020 campaign and what to do next. In the middle of that, the White House without warning decided to drop a political bomb that plays to the Democratic Party’s strength.

Senate Republicans are so disinterested, they didn’t bother asking Trump any questions about his plans for healthcare when he joined them for their weekly conference lunch on Tuesday. Off of Capitol Hill, Republican insiders were dismissive, worrying that Trump’s haphazard approach will result in voters blaming the party for consequences of Obamacare being ruled unconstitutional.

Some Republicans worry that insurance companies could throw people off of their existing plans if Obamacare is ruled unconstitutional, creating the same upheaval that drove voters into the arms of the GOP when the Affordable Care Act was implemented.

[Also read: Federal judge strikes down Medicaid work requirements]