(CNN) President Donald Trump can't seem to get Nancy Pelosi out of his head, even as most of the rest of the nation enjoys a holiday halftime break from the impeachment drama.

His anger is boiling as the politics of impeachment evolve in a slow burn over the Christmas and New Year break, with pressure rising on senators of both parties over his coming Senate trial.

Trump, between rounds of golf and greeting guests at his Mar-a-Lago resort in Florida, keeps returning to vent fury at the House speaker who led his impeachment a week ago.

"Nancy Pelosi's District in California has rapidly become one of the worst anywhere in the U.S. when it come to the homeless & crime," Trump tweeted on Thursday. "It has gotten so bad, so fast - she has lost total control and, along with her equally incompetent governor, Gavin Newsom, it is a very sad sight!"

In a string of tweets, Trump complained about Pelosi's decision not to send the articles of impeachment to the Senate until she learns about GOP plans for the shape of his trial. He speculated about the unlikely prospect that the California Democrat could lose a primary -- in a district where her political exposure comes from the left, not from her right.

He also slammed the speaker for impeaching him at all, insisting he did nothing wrong in his dealings with Ukraine, while quoting conservative pundits who were critical of Pelosi.

The Democratic-led House last week passed articles of impeachment alleging abuse of power and obstructing Congress, over the President's pressure on Ukraine for political favors.

The President's feud with Pelosi is a reminder that the House speaker has been one of the few Washington players who often get the better of a President who loves to lay down the law.

Stung by the historic stain of impeachment, Trump might at least by now have been looking forward to a Senate trial that is expected to easily acquit him. But Pelosi's move -- designed to boost leverage of Senate Democrats tussling with the GOP over the makeup of the trial -- has deprived the President of peace of mind on impeachment over his two-week holiday break.

Democrats turn up the heat on McConnell

Talks between Senate Majority Leader Mitch McConnell and Minority Leader Chuck Schumer have hit an impasse over the question of witnesses. There is little apparent prospect of a breakthrough until the new year.

Schumer, a New York Democrat, wants McConnell, a Kentucky Republican, to call testimony from officials like former national security adviser John Bolton and White House acting chief of staff Mick Mulvaney. Trump had refused to let either man testify for the House impeachment investigation. But the Senate GOP leader argues that conducting investigations and improving the Democratic case is not the Senate's job.

Democrats are spending the holiday seeking to pile pressure on McConnell, apparently trying to saddle Republicans with the politically damaging picture of an unfair trial.

"I think you'll see Republicans rise to the occasion," Rep. Steve Cohen, D-Tennessee, said Thursday on "CNN Newsroom."

"They would not want to besmirch the reputation of the body in which they serve, in which they would like to contribute to its stellar position as a place of respect in the United States' system of government," Cohen said.

"And I think they'll support a fair trial."

Democrats have seized on comments by Republican Sen. Lisa Murkowski of Alaska expressing concern at McConnell's statements that he is coordinating closely with the White House on the trial.

"In fairness, when I heard that, I was disturbed," Murkowski, a moderate, told KTUU, a CNN affiliate.

"To me, it means that we have to take that step back from being hand in glove with the defense, and so I heard what Leader McConnell had said, I happened to think that that has further confused the process," Murkowski added.

Rep. Dan Kildee of Michigan, who is part of the House Democratic leadership team, said such comments should cause a rethink from McConnell.

"He should listen to his fellow senators, particularly Republican senators like Sen. Murkowski, who is expressing what I think what is a very broadly held view," Kildee told CNN.

"Mitch McConnell should not be coordinating and fully responding to the White House when it comes to how he determines to conduct this trial."

Some Democrats face tough trial vote

But Democratic leaders may have trouble presenting a united front against the President in the Senate, given recent comments by one vulnerable senator in the party, Doug Jones of Alabama.

Jones, who comes from a state Trump is expected to win big in 2020, said over the weekend that he wanted the "dots" to be connected before deciding how to vote in the trial.

"What I really want to see, though, is to fill in the gaps," Jones said on ABC's "This Week."

Kildee, however, argued that senators had a greater duty in a trial than merely to take current politics into account.

"I think the Senate, in a case like this, every senator is going to have to answer not just to their constituents in this moment. But as I have said in the past, to the future, in my case, I think about my grandchildren. We're going to have to answer for how we acted," he told CNN's Ryan Nobles.

Other senators often seen as possible defections from Democratic ranks during a Senate trial include Kyrsten Sinema of Arizona and Joe Manchin of West Virginia.

Any Democratic vote to acquit the President would give Trump and other Republicans the propaganda win of being able to argue that he had been acquitted in the Senate trial by a bipartisan majority.

Still, there is also political heat on some Republicans, who could stand to lose if the trial is seen as unfair.

Colorado's Cory Gardner and Maine's Susan Collins, who face difficult reelection races in swing states, must wrestle with the delicate politics of impeachment. Voting to acquit Trump could anger more moderate voters. But both senators could be helped by a backlash against impeachment by the pro-Trump base in November that could help them outperform the President.