Senator Cory Booker spoke in an all-night session on the Senate floor early Tuesday, in an effort to seize the national spotlight and criticize the Trump administration’s policies on health care, Social Security, education and much else.

Mr. Booker, Democrat of New Jersey, began speaking on Monday evening and said he planned to continue for as long as he was “physically able.” He was still going as of 5 a.m. Eastern time.

The speech focused in part on what Mr. Booker said were President Trump’s plans to cut funding for Medicaid, among other programs. The White House has denied that it plans to cut Medicaid benefits, but the president and his allies have attacked Medicaid, Medicare and Social Security over what they claim is waste, fraud and abuse.

“I rise with the intention of disrupting the normal business of the United States Senate for as long as I am physically able,” Mr. Booker said near the start of his speech. “I rise tonight because I believe sincerely that our nation is in crisis.”

Mr. Booker — wearing a dark suit and tie, and an American flag pin — stopped speaking to allow questions from fellow Democrats, including Senator Chris Murphy of Connecticut, without formally relinquishing the floor.

His speech was not a filibuster — a procedural tactic that has been used to block legislation on many issues, including civil rights — because it did not come during a debate over a specific bill or nominee. But it could still disrupt official business if it continues past noon, when the Senate is scheduled to convene.

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