West Palm Beach, Florida (CNN) President Donald Trump once hoped to leave Mar-a-Lago fortified by a reprieve from Washington and secure of a vindictive Senate impeachment trial upon his return.

Now, the President returns to the White House facing the potential for dramatic conflict with Iran just as his conduct and judgment as commander-in-chief are poised to go on trial. Some of his allies are concerned there hasn't been sufficient preparation for what will undoubtedly be a decisive moment of Trump's presidency. Others believe the Iran situation could bolster Trump at a potentially fateful juncture as Democrats try to remove him from office.

"It is ashame (sic) that the Democrats make us spend so much time & money on this ridiculous Impeachment Lite Hoax," Trump wrote on Saturday, even as Iran was warning of attacks on American military assets in the region. "I should be able to devote all of my time to the REAL USA!"

It was a sign that impeachment remains very much on Trump's mind, even as his national security team prepares for potential reprisals for the killing by US drone of Qasem Soleimani, Iran's top military commander, near the Baghdad airport.

Key questions

Key questions remain unanswered about the Senate trial, including when it will begin, how long it will last or whether witnesses will be called, as House Speaker Nancy Pelosi continues to hold off transmitting the two articles of impeachment passed by the House last month.

That has left Trump's team without a clear guide in their preparation efforts, which administration officials said proceeded apace at the White House even as Trump spent his days at the golf course or mingling with guests at Mar-a-Lago.

Trump was returning to Washington on Sunday evening after more than two weeks at his South Florida estate. While the Iran situation required Trump to attend regular briefings with his national security team, people close to the President said he also seemed focused on impeachment and the upcoming election year during conservations at his clubs.

Indeed, Trump was midway through an election-year strategy session at Mar-a-Lago on Thursday evening when he excused himself to be updated on the strike -- which he'd approved days earlier -- inside a secure room on the property, a person familiar with the matter said.

People who spoke with Trump over the holiday said his spirits appeared high, even as he remains aggrieved at being impeached. The President was "pleased" with his strike on Soleimani and justified the operation to advisers and friends by pointing to US service members who have lost limbs in Iraq, another person familiar with Trump's discussions said, though he did not appear concerned about the blowback.

"He doesn't think about the implications," the person said.

Crucial decisions

At Mar-a-Lago, Trump was keen as ever to sound out his friends' opinions of the impeachment predicament, according to people who spoke with him. Aides had warned ahead of the trip that crucial decisions about his impeachment defense needed to be made during his two-week hiatus, but the White House has still not locked down a defense strategy or team.

As the White House awaits Pelosi's next move, the counsel's office has been drafting multiple lines of approach and preparing for any outcome, according to White House officials. That includes contingencies should the trial include witness testimony -- though aides now say that seems unlikely -- and trying to map out potential formats for the proceedings.

The biggest obstacle facing Trump, according to people close to him, is deciding who will represent him during the impeachment trial alongside Pat Cipollone, the White House counsel. Trump has polled at least a dozen people, some of them repeatedly, about who would do the best job in representing him.

Options still include attorneys famous for their television punditry, such as Alan Dershowitz, whom Trump was spotted engaging on Christmas Eve at Mar-a-Lago. Trump has also considered asking some of his staunchest allies in the House to participate. Jay Sekulow, another one of the President's private attorneys, is expected to play a role in the Senate trial, though his responsibilities are still unclear. Trump has said repeatedly that he wants Sekulow on the team, two people familiar with the matter said.

As of now, the plan is for both Cipillone and Sekulow to deliver both opening and closing statements, a person familiar with the legal team's strategy said. Who else might participate in the opening and closing statements remains fluid.

The main message Trump received this week was one of reinforcement, according to aides, whether on the ninth hole or dining on hot dogs covered in relish inside the clubhouse. On New Year's Eve, he was seen locked in conversation with his personal attorney Rudy Giuliani and the conservative television host Lou Dobbs, who has provided fawning coverage of the President on his nightly program.

Iran strike

The politics surrounding impeachment have only been complicated by the strike killing Soleimani. Already, both the President's allies and his opponents have linked the two, with Democrats claiming the strike was a distraction effort and Republicans alleging Trump is willfully being undermined as the country faces a national security crisis.

"Donald Trump was just impeached a week and a half ago, and we need to get to the bottom of how and who helped him carry out this illegal cover-up," Rep. Debbie Wasserman Schultz, D-Florida, said on CNN last week. "That's outrageous, and I think that has a lot to do with what this attack was about."

Rep. Kevin McCarthy of California, the House Republican leader, adopted an opposite view.

"It is very sad about the Speaker of the House," he said on Fox News on Saturday. "Soleimani killed 600 Americans and she is now questioning. She would rather stand with Hollywood, with Rose McGowan than to stand with our servicemen and women and make sure they're protected. That to me is an abuse of power."

McCarthy, who was with the President on Thursday evening as the strike was carried out in Iraq, was one of several Republican lawmakers who visited Trump at his club during the holiday break.

Legal team

Largely absent from Mar-a-Lago were any of the White House's lawyers, who have been spending their holiday weeks holed up in the suite of second-floor West Wing offices occupied by the counsel's team.

Instead of traveling to Mar-a-Lago during the second week of the President's trip as initially planned, Cipollone remained in Washington, according to people familiar with the matter. He has spoken frequently with Trump, senior adviser Jared Kushner and several lawmakers about the impeachment trial.

Cipollone, a taciturn litigator who has developed a close relationship with the President, has spent much of his time over the past weeks interviewing those who could potentially help with the Senate trial, whether it's making opening statements, presenting evidence or playing a behind the scenes role in crafting the strategy.

Trump has also indicated to aides that he's keenly interested in who will be defending him on television when the trial concludes for the day, demanding his strongest surrogates be booked for interviews.

Before the President departed Washington for his Christmas vacation in West Palm Beach, CNN reported that aides were concerned about the level of outside influence on the him as he awaited his impeachment trial. Aside from Giuliani and Dobbs, Trump was seen this week golfing with former Congressman Trey Gowdy and Sen. Lindsey Graham, lunching with the radio personality Rush Limbaugh, and discussing his standing with Liberty University President Jerry Falwell Jr.

Graham was included in at least one briefing with administration officials about the plans to strike Soleimani, he said later, though he and Trump also discussed impeachment during his time in Florida.

Asked on Fox News Sunday whether Trump's impeachment had led some American enemies to deem him vulnerable, Secretary of State Mike Pompeo answered curtly.

"You should ask Mr. Soleimani," he said.

CNN's Jim Acosta contributed to this report.