Washington • President Donald Trump took fresh aim Thursday at retiring Sen. Jeff Flake, R-Ariz., mocking his “record low polling numbers” in his home state and questioning how he could possibly be thinking about running for office again.

Flake, who has not ruled out a Republican primary challenge of Trump in 2020, is a frequent Trump critic and released excerpts Wednesday night of a floor speech he plans to deliver accusing the president of providing “not grown-up leadership” on trade.

“How could Jeff Flake, who is setting record low polling numbers in Arizona and was therefore humiliatingly forced out of his own Senate seat without even a fight (and who doesn’t have a clue), think about running for office, even a lower one, again?” Trump wrote. “Let’s face it, he’s a Flake!”

It was not clear to which lower office Trump might be referring.

Flake stoked speculation about a 2020 challenge to Trump in March, when he traveled to New Hampshire, the nation’s first primary state, to deliver an address to a crowd of business leaders and political activists. In his speech, he decried the “degradation of the United States and her values” by the current occupant of the White House.

In his speech at the Politics & Eggs breakfast — long viewed as an obligatory stop for potential presidential candidates — Flake said he hopes a serious Republican does challenge Trump.

“I think that the Republicans want to be reminded what it means to be a traditional, decent Republican,” he said.

In announcing his decision to retire rather than seek re-election this year, Flake said that his party had turned sharply to the right, making it impossible for him to win the Republican nomination to seek another term unless he toed the line on Trump’s actions.