Top Republicans loyal to President Trump are already jockeying to succeed him in 2024 - or even in 2020, an unusual dynamic spawned by the uncertainty of a White House invariably embroiled in controversy.

The moves are subtle and can be plausibly explained as something other than preparation for a presidential run. Secretary of State Mike Pompeo is in early primary campaign battleground Iowa to reassure voters about Trump’s trade policy. Nikki Haley, former ambassador to the United Nations, has formed a conservative nonprofit to influence policymakers. Vice President Mike Pence’s well-developed political operation was built to service his boss.

But GOP insiders concede that politically ambitious Republicans such as these three have ulterior motives.

“A couple of people are trying to be prepared in case Trump didn’t run for some reason,” Charlie Black, a veteran Republican operative, told the Washington Examiner. “The others are keeping their powder dry and just trying to position themselves for ’24.”

On Monday, House Democrats announced a major expansion of investigations into Trump. In combination with multiple existing probes targeting the president, his associates, and family business empire, some Republicans are bracing for the possibility that he might be driven from office or declare victory and retire.

For the most part, Republicans firmly expect Trump and Pence to lead the party’s ticket next year. The president enjoys a sky-high job approval rating of around 90 percent with self-identified Republicans in most public opinion polls, and there is nothing he likes more than delivering a stem-winder to a friendly crowd. But doubts linger as the investigations pile up.

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The report from special counsel Robert Mueller on the federal probe into whether Trump or his campaign colluded with Russia in 2016 is coming any day. Meanwhile, a New York branch of the Justice Department is investigating Trump and those connected to him. Add to that the Democrats in the House, who are using their new power to initiate multiple far-reaching inquiries after winning control of the chamber in the midterm elections.

Skepticism about Trump’s future is especially pronounced among renegade Republicans working on a long-shot effort to block the president from re-nomination in the 2020 primary. “We don’t know what it’s going to be like next week, next month, or this summer or fall,” said Maryland Gov. Larry Hogan, a Republican who has not ruled out challenging Trump, in a recent interview with the Washington Examiner.

In the upper echelons of the Republican Party, opinions on Trump’s staying power vary widely.

From a logistical standpoint, some expect him to run virtually regardless of any legal or ethical baggage and have come to terms with that regardless of personal preference. In that regard, these Republicans tend to interpret the early jockeying for a post-Trump future as all about 2024.

“You'd see a lot more Republicans going to Iowa and New Hampshire if they thought there was a realistic chance Trump didn't run for re-election,” said Alex Conant, a Republican consultant who advised Sen. Marco Rubio, R-Fla., in 2016. “To the extent this activity is an indication of White House ambitions, it's all about 2024.”

Other Republican insiders attribute the early maneuvering by presidential aspirants to an ambiguity about Trump’s long-term impact on the party. Most Republicans interested in occupying the White House after Trump don’t share his populism, and that has sparked a battle to define the future of the party possibly six years before that future comes.

“There isn’t going to be a political legacy of the Trump administration that includes generations of mini-mes,” a senior Republican strategist said.