WASHINGTON, Jan. 23 (Xinhua) -- U.S. House managers, a group of seven Democrats acting as prosecutors, tried on Thursday to convince senators that President Donald Trump abused the power of his office, as his impeachment trial entered its third day.

"Trump abused his authority as commander-in-chief and chief diplomat to benefit himself," said Adam Schiff, the lead manager who as House Intelligence Committee chairman has led the impeachment inquiry.

"And he betrayed the interests of the American people when he did so," the California Democrat added.

Abuse of power is the charge of one of the two articles of impeachment against Trump that were passed in the Democratic-controlled House in December, making him the third president in U.S. history to be impeached.

The president has been accused of benefiting himself in the upcoming 2020 presidential election by asking Ukraine to investigate his political rivals.

In urging the Senate to convict Trump and remove him from office, House Judiciary Committee Chairman Jerry Nadler said during his presentation that the U.S. Constitution "does not leave us stuck with presidents who abuse their power in unforeseen ways that threaten our security and democracy."

"No one anticipated that a president would stoop to this misconduct and Congress has passed no specific law to make this behavior a crime," said the New York Democrat, also an impeachment manager. "Yet this is precisely the kind of abuse that the framers had in mind when they wrote the impeachment clause."

Stretching over nine hours, concluding past 10 p.m. ET (0300 GMT), Thursday's session made many senators, who by impeachment rules are not allowed to speak when hearing arguments, feel fatigued. "They're laying out their case multiple times," James Lankford, a Republican senator from Oklahoma, said of the House managers' arguments.

"They spent a lot of the big chunk of the center part of the day, really, talking about things that are not relevant or that are policy issues -- for instance, firing an ambassador -- not taking the advice of career professionals. All those things, those are not impeachable," he said.

On Friday, the last day allotted to the managers to present their case, Democrats will make their final move to prove that Trump obstructed Congress.

Then on Saturday, Trump's legal defense team will take the stage to refute the managers' claims and argue for the president.

Senators and aides of both parties are reportedly expecting a shorter, morning-only trial session on Saturday, with senators allowed to leave town for weekend.