(CNN) Congressional Republicans spent last weekend huddling with President Trump at Camp David to frame their legislative agenda in 2018. But they have already placed the bets most likely to determine their fate in November's midterm election, as a series of dramatic events late last week demonstrated.

Two of their biggest decisions over the past year already loom over the upcoming election.

The first has been to align more closely with Trump even as questions have mounted about both his basic fitness for the presidency and the potential legal exposure that he and his inner circle might face in the investigation of special counsel Robert Mueller. The second has been to pursue a policy agenda, on issues from taxes to health care to the environment, aimed almost entirely at the preferences of their party's conservative base, with strikingly few concessions to any voices or interests beyond their core coalition.

Before November, the GOP might modulate each of these choices. But Republicans have engraved the fundamental outline of each direction so deeply over the past year that they are unlikely to be significantly altered.

The decisions to increasingly lock arms with Trump and to pursue such a partisan agenda reflect the same political calculation. On each front, Republicans are placing the highest priority on maximizing unity and enthusiasm among their base voters -- even at the price of infuriating and energizing Democrats, and antagonizing more swing voters -- especially suburban college-educated whites. For voters anywhere on the continuum from ambivalent to alarmed about Trump, congressional Republicans are now sending a clear signal that they are far more inclined to empower than to constrain him.

"During the campaign, they were making a bet -- and it's clear that it's a misplaced bet -- that once Trump became president they could control him and contain him and he would somehow rise above what he was during the campaign," said Pete Wehner, the director of strategic initiatives in the George W. Bush White House. "And it's been the opposite. Once they made that deal with the figurative devil, they were stuck. They are on the train and they don't think they can get off."

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A succession of rapid-fire events late last week encapsulated each of the GOP's two key wagers.

Last Thursday morning came widespread excerpts from the scabrous new book by Michael Wolff, "Fire and Fury: Inside the White House," that alleged virtually all of the administration's officials privately mock Trump's capacity and despair over his impulsiveness and refusal to process almost any information they present him. Both Trump and the White House have dismissed the claims. But the charges -- deepened when Wolff's full book was released Friday and he appeared in his first television interviews -- underscored the President's greatest political vulnerability: the conclusion among many voters that he is not equipped -- by judgment, temperament, values or experience -- to meet the demands of his office.

A few hours after Wolff's first revelations came another body blow: the report last Thursday night by The New York Times that Trump, through his White House counsel Donald McGahn, had pressured Attorney General Jeff Sessions not to recuse himself in the Russia probe. That reporting underscored the president's potential legal vulnerability to charges of obstruction of justice in Mueller's probe. So did a succession of spectacular charges in Wolff's book, including a report that Trump personally directed the misleading statement about the meeting of his son Donald Trump Jr. and other top advisers with Russians offering "dirt" on Hillary Clinton in June 2016.

CNN has not independently verified all of the details in Wolff's book.

Any of these revelations might have been expected to provoke alarms from congressional Republicans. But no leading Republican raised an eyebrow about the accusations in Wolff's book. And bookended around the reports of White House pressure on Sessions, House and Senate Republicans each pushed to intensify investigations not against Trump but rather the authors of the "dossier" that initially raised charges of Russian meddling and connections with his campaign.

On Wednesday, House Speaker Paul Ryan sided with House Intelligence Chairman Devin Nunes, a fierce Trump defender, in demanding new documents from the Justice Department outlining how it handled the dossier. And on Friday, Republican Sens. Chuck Grassley and Lindsey Graham further raised the stakes by asking the Justice Department to open a criminal investigation against Christopher Steele, the former British spy who authored the dossier.

This push to shift the investigative focus from Trump to his critics followed the broader direction among congressional Republicans, who are embracing the President more unreservedly, and defending him more reflexively, than they did when he took office.

"It seems to me a pretty bottomless well," said Wehner, now a senior fellow at the conservative Ethics and Public Policy Center, and a frequent Trump critic. "If there is some line Trump can cross that can cause them to stand up to him, we haven't seen it."

Sandwiched between the release of Wolff's excerpts and the McGahn reporting, the Trump administration issued a major policy announcement that helps explain that evolution. Interior Secretary Ryan Zinke announced that the administration intends to open virtually all of the country's coastal waters to offshore drilling by oil companies. The plan proposed 47 lease sales over the next five years covering some 1.5 billion acres of offshore waters. In each case that was more than even President Ronald Reagan and his controversial interior secretary, James Watt, proposed in 1982 (41 lease sales and about 1 billion acres), before a bipartisan coalition in Congress forced them to retrench their plans in a landmark political battle of that era.

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The offshore oil announcement fit the clear policy pattern of Trump's first year: It granted virtually every wish of a key component in the GOP coalition -- in this case the oil industry -- with virtually no concession to any interests outside that coalition, from environmentalists to the mostly Democratic governors of coastal states. The same uncompromising pattern has been evident in Trump's efforts to repeal the Affordable Care Act; the administration's moves to rescind an array of Obama-era environmental and consumer safety regulations; Trump's succession of highly ideological federal judicial nominations; and the recently passed tax bill, which not only directed the vast majority of its benefits to the highest earners but also punished Democratic-leaning states by limiting the deductibility of state and local taxes. (For that reason, New York Gov. Andrew Cuomo last week called the tax plan "economic civil war.")

On elements of his America First nationalism -- particularly his skepticism about trade, legal immigration and foreign alliances -- Trump may eventually spark more resistance from mainstream Republicans and their allied business interests. But so far his willingness to advance so many long-standing conservative causes has clearly encouraged more Republicans initially skeptical about his fitness to lash themselves more tightly to his turbulent presidency.

"You would have to say that the tax cut/corporate wing of the party has gotten what it signed up for and the social conservatives have certainly gotten what they signed up for," says William Galston, a senior fellow at the Brookings Institution and former deputy domestic policy adviser to President Bill Clinton. "And the portion of the agenda that is being pursued through administrative action, rather than legislation, is very much in line with what a more traditional Republican conservative would have done. ... The coalition as it existed before Trump came on the scene is getting paid off big time."

Given the policy rewards, both Wehner and Galston are dubious that almost any provocation from Trump could cause either congressional Republicans or the broader conservative movement to establish more independence from him, unless voters send a clear message of discontent in 2018.

This approach increases the odds that the core Republican coalition will remain united heading into 2018 but magnifies the risk of alienating voters beyond it. Polls have shown that cornerstones of the Trump agenda -- led by the ACA repeal and the tax bill -- face enormous resistance from Democrats and independents. It was revealing that neither the ACA repeal effort, nor, even more remarkably, the tax cut bill, could draw support from a single Democrat in either chamber -- even though 10 Senate Democrats are seeking re-election in states Trump carried in 2016.

Even more important, surveys have consistently found that Trump's performance in office has convinced a solid majority of Americans that he lacks the temperament , skills and even stability they expect in a president. By choosing not to provide any meaningful check or oversight on Trump, congressional Republicans risk convincing those dubious voters that the only way to constrain the president is through a Democratic-led Congress. Indeed, in a December national Quinnipiac Poll 56% of Americans said they believed Trump is not qualified to serve as president -- and fully 83% of those critics said they intended to vote Democratic for Congress.

"What's happened now is a strong majority of the country has decided that they deeply oppose Donald Trump, and it's not based primarily on policy," notes Wehner. "It's based primarily on their judgment that he's not fit to be president. The Republican Party is in a position of standing there and making the opposite argument -- and there's going to be a price for that."