WASHINGTON >> President Donald Trump turned up the heat on Attorney General Jeff Sessions today, launching a fresh Twitter tirade against him while musing privately about firing the man who was the first U.S. senator to endorse his candidacy.

Pressure on the nation’s top law enforcement officer to resign mounted by the hour, even as fellow Republicans began to push back against Trump’s extraordinary public rebuke of his Cabinet officer.

The president’s latest broadside came in the form of early morning tweet: “Attorney General Jeff Sessions has taken a VERY weak position on Hillary Clinton crimes (where are E-mails & DNC server) & Intel leakers!”

Trump’s intensifying condemnation of Sessions has fueled speculation that the attorney general may step down even if Trump opts not to fire him though several people close to the former Alabama senator have said he does not plan to quit.

The president’s anger over Sessions’ decision to recuse himself from the government’s investigation of Russian meddling in the U.S. election burst into public view Monday when Trump referred to Sessions in a tweet as “beleaguered.”

Privately, Trump has speculated to allies in recent days about the potential consequences of firing Sessions, according to three people who have recently spoken to the president. They spoke on condition of anonymity to discuss private conversations.

But the president’s ongoing criticism of Sessions drew a fiery response from one of his former Senate colleagues today, suggesting that all Republicans may not fall in line behind any effort to oust the attorney general.

“Jeff Sessions is one of the most decent people I’ve ever met in my political life,” said South Carolina Sen. Lindsey Graham. “President Trump’s tweet today suggesting Attorney General Sessions pursue prosecution of a former political rival is highly inappropriate.”

Sens. Richard Shelby of Alabama, Thom Tillis of North Carolina and others also voiced support of their former colleague. But the White House only cranked up the pressure on Sessions, risking inflaming the Senate on the day it was set to move on the GOP health care plan.

Anthony Scaramucci, the president’s new communications director, said in an interview with radio host Hugh Hewitt that Trump is “obviously frustrated” and that the two men “need to work this thing out.”

Scaramucci then replied “you’re probably right” when Hewitt said it was clear that Trump wants Sessions gone.

And White House press secretary Sarah Huckabee Sanders told Fox News’ “Fox & Friends” that the president was “frustrated and disappointed” with Sessions for recusing himself from the Russia probe.

“That frustration certainly hasn’t gone away. And I don’t think it will,” she said.

House Speaker Paul Ryan said merely that “the president gets to decide what his personnel is.”

Trump often talks about making staff changes without following through, so those who have spoken with the president cautioned that a change may not be imminent or happen at all.

Trump’s Twitter onslaught began Monday, when he deemed Sessions “beleaguered” and asked why he wasn’t “looking into Crooked Hillarys crimes & Russia relations?”

His rapid-fire postings resumed at daybreak today, with the president wondering aloud about Sessions’ “VERY weak” position on “Hillary Clinton crimes.” And then again, as he tweeted about “Ukrainian efforts to sabotage Trump campaign — quietly working to boost Clinton. So where is the investigation A.G.”

But despite his campaign promises to “lock her up,” it was Trump himself who signaled during the transition that he was not going to appoint a special prosecutor to go after Clinton.

If Sessions departs, several scenarios could unfold. If Trump follows his own executive order outlining a succession plan, Deputy Attorney General Rod Rosenstein would become acting attorney general until a successor was nominated and confirmed by the Senate. That would leave the president with another attorney general of whom he has been sharply critical in both public and private for his handling of the Russia probe, according to four White House and outside advisers.

But a federal law also would let him circumvent that by temporarily filling the vacancy with someone of his choice who has already been confirmed by the Senate to another position. That could include Cabinet members or other top Justice Department officials— as long the attorney general resigned as opposed to being fired, said University of Texas law professor Stephen Vladeck.

Another option called a recess appointment would allow Trump to appoint anyone of his choosing to be attorney general while the Senate recesses for 10 days or more in August. This would allow him to bypass Senate confirmation until 2019.

Sessions’ exit could also raise the specter of Trump asking Rosenstein — or whomever he appoints to fill the position — to fire Robert Mueller, the special counsel leading the investigation into Russia’s meddling in the 2016 election and potential collusion with Trump’s campaign. That would seem to fulfill the vision of the Justice Department that Trump’s critics believe he articulated during the campaign: a place that, at his direction, will punish his political enemies.

Trump has seethed about Sessions’ decision to recuse himself from the investigation for months, viewing it as disloyal and resenting that the attorney general did not give the White House a proper heads-up before making the announcement. His fury has been fanned by several close confidants — including his son, Donald Trump Jr. who is also ensnared in the Russia probe — who are angry that Sessions made his decision.

Sessions and Trump used to be close, sharing both a friendship and an ideology, particularly on immigration. But their conversations in recent weeks have been infrequent. Sessions recently asked senior White House staff how he might patch up relations with the president, but that effort did not go anywhere, according to a person briefed on the conversations.

Associated Press writers Sadie Gurman and Eric Tucker contributed reporting.