The nominees for several key Cabinet posts in the new administration of President-elect Donald Trump caught officials in Washington off guard this week and ignited a firestorm of criticism — not all of it from Democrats.

At this point, the newly elected Senate Majority Leader John Thune of South Dakota is hedging his bets. "None of this is going to be easy," he said Thursday.

That is an understatement as at least four of Trump's second-term picks to date could qualify as a "problem nominee." Any one of them could be the focus of negative media coverage and the cause of enormous discomfort for Republican senators who must vote to confirm.

Trump has made clear he expects his party members to fall in line, and if they don't, he has often found ways to get around them. Thune is respected by his colleagues and well liked by his GOP confreres. He worked hard and raised impressive sums of money to help his party seize back the majority this fall. But soon he will essentially face a choice between Trump's demands and the political and personal preferences of the Republican senators who chose him as leader. When those coincide, as they usually will, fine. When they don't, Thune will need to find a compromise or choose sides.

The lanky South Dakotan faces a tall order. Trump has made clear he does not regard the Senate's constitutional duty to advise and consent in such appointments as sacrosanct. He wants to be allowed to fill these offices by use of the "recess appointment" power. Originally created to deal with true emergencies and the difficulties of 18th century travel, this power has been used now and then to get around a recalcitrant Senate.

President George W. Bush used it to install John Bolton as U.S. ambassador to the United Nations in 2005 (circumventing a Senate committee that included senior Democrat Joe Biden and a first-term member named Barack Obama.) Bolton did serve in the job on that basis and has continued his long-running career as a leading hawk on military and foreign policy. He was even Trump's national security adviser during his first term.

That experience led Bolton to write a scathing critique of Trump in 2020. This week he called Trump picking Tulsi Gabbard to serve as his director of national intelligence (DNI) "the worst Cabinet-appointment in history."

The week started calmly enough with the news that Trump wanted Florida Sen. Marco Rubio to be his secretary of state. Senators rarely object to having one of their own elevated to Cabinet status, so long as they are as politically reliable as Rubio has been.

Real trouble started brewing with Pete Hegseth, an Army vet known for his weekend commentary on Fox News, being named secretary of defense. Although a veteran of the Iraq and Afghanistan missions, he does not have the background that senators have come to expect of someone appointed to head up the Department of Defense. Hegseth's frequent attacks on the uniformed leadership of the armed services has included talk of firing current generals, including at the highest levels. Some outside observers found it hard to believe Trump was serious about the choice, suggesting the president-elect was mostly giving the Pentagon a shot across the bow.

But Trump 2.0 was just getting started.

Consider Tulsi Gabbard, Trump's choice as the new director of national intelligence. Gabbard is another veteran who has been critical of "forever wars." She was also briefly a Democratic member of the House before becoming a Trump fan. But all that would be little or no problem for the senators.

Here's what could be: Gabbard has no senior military or national security experience and acquired a reputation as a defender of Vladimir Putin and the Russian invasion of Ukraine, which she blamed on the hostile posture of President Biden and the NATO alliance toward Russia. Commentators, including some conservatives, have wondered aloud just how deep Gabbard's sympathy with Putin's positions might go.

Yet these burgeoning controversies were eclipsed by news that Trump had chosen embattled Florida Rep. Matt Gaetz to be his attorney general. Gaetz has been the subject of a House Ethics Committee investigation into sex trafficking and drug-use allegations that began in 2021. Gaetz abruptly resigned from Congress before a committee report could be released. Speaker Mike Johnson then urged the committee not to release its report.

The allegations had also been investigated by the FBI but no charges were filed. Gaetz had denounced it all as another anti-Trump witch hunt.

Gaetz has made it clear his ire at the Department of Justice is as intense as Trump's own.

Gaetz has some fans in the Senate but more than a normal share of critics there too. If you get all your news from TV, you might well think his nomination is the biggest story since, well, the last Trump-linked scandal or outrage. Moderate senators are voicing concerns while also noting the importance of the Senate's advise and consent process.

And then, to top off a week of show stoppers, Trump announced that the anti-vaccine activist and former independent presidential candidate Robert F. Kennedy Jr. would be his secretary of Health and Human Services Department. That gives him responsibility for the Food and Drug Administration, the National Institutes of Health and countless programs providing medical care and protecting the public. Trump said he and Kennedy would "make America safe and healthy again."

There have been controversial choices in the past, but these choices seemed highly likely to antagonize the agencies they would be overseeing. Indeed, that appeared to be the intent.

If there were just one controversial nominee taking all the heat, a withdrawal of a defeat in committee or on the floor might seem likely — or even probable.

But in the 119th Congress, it is far from certain that a meaningful number of Senate Republicans will show up to oppose any of these nominees. They may make their objections known in a variety of ways, including off-the-record comments. But it will not matter unless at least four of them band together to make a unified stand in the 53-47 Senate. But that could carry enormous consequences for the few GOP senators who held out.

Trump is renowned for his rhetorical bluster and force of personality. His supporters can swarm the internet and amplify these effects. But as unpleasant as such a flaming must be, at least a few senators have shown they can withstand a bit of heat.

What they are likely concerned by are Trump's voters, especially now that Trump has won a second election and carried the popular vote as well as his biggest share yet of the Electoral College.

Republican officeholders know Trump's voters are largely their voters. They know that if they run again they will need these votes in the general election and quite possibly in a Republican primary as well.

Not every Republican voter would resent having his or her senator stand up to Trump, not by a longshot. But be prepared for Republicans in the Senate to calculate that opposing Trump on anything notable in the next two years is inviting a primary challenger in their next election cycle.

And even if incumbents feel confident they can mend fences in the meantime and beat back a primary challenge, primary fights drain their campaign resources. They also force incumbents to take a harder partisan line to hang on to the nomination. And they give a president of the same party a considerable degree of leverage. That has long been the case, even before the personality of Trump was involved.