Washington (CNN) Donald Trump's legal team will wrap up its defense of the President in a short two-hour summing-up on Tuesday after arguing that new revelations by former national security adviser John Bolton are irrelevant to the impeachment trial despite Democratic demands that he be called to testify.

In a manuscript of his forthcoming book first reported by The New York Times , the former national security adviser says Trump ordered him to maintain a hold on US military aid to Ukraine until it agreed to investigate former Vice President Joe Biden.

At the end of a long day of trial arguments on Monday that largely ignored the new Bolton drama, Alan Dershowitz, the Harvard emeritus professor who joined Trump's defense team, argued that even if Bolton's reported claim was true, it would not amount to an impeachable offense.

He made a case for expansive presidential power, saying that a quid pro quo alone does not amount to an abuse of power -- the basis of the first article of impeachment -- which he said was not sufficient in itself to justify ending a presidency.

"Nothing in the Bolton revelations, even if true, would rise to the level of an abuse of power or an impeachable offense, that is clear from the history. That is clear from the language of the Constitution," Dershowitz said in comments that could arm Republicans -- who are on the spot amid calls for Bolton to testify -- with a new argument.

But Sen. Jeff Merkley told CNN's Dana Bash Tuesday that Dershowitz's theory would in effect hand presidents the ability to interfere in elections and escape consequences.

"I really thought Dershowitz disgraced himself," the Oregon Democrat said.

"Because he said essentially even if a President commands the power of state to corrupt a future election, by seeking the intervention of a foreign power, that that's not something that impeachment would be appropriate for. It's exactly the type of foreign interference that the founders talked about."

Trump has repeatedly made rump has repeatedly made unfounded and false claims to allege that the Bidens acted improperly in Ukraine. There is no evidence of wrongdoing by either Joe Biden or his son Hunter Biden, who was on the board of a Ukrainian energy firm.

The Times report on Bolton complicated life for a handful of Republicans who are under pressure from Democrats to vote for fresh witnesses who did not testify to the House investigation following Trump's vow to avoid cooperating with the impeachment push.

"The reporting on John Bolton strengthens the case for witnesses and has prompted a number of conversations among my colleagues," Maine's Sen. Susan Collins said.

Utah's Sen. Mitt Romney added: "I think with the story that came out yesterday that it is increasingly apparent that it would be important to hear from John Bolton."

But despite the new focus on Bolton, there is no sign yet that four Republican votes will be forthcoming to piece together a 51-vote majority that would be needed to call new witnesses.

Several Republicans seemed pleased by Dershowitz's presentation, according to CNN reporters in the chamber on Monday night.

Tuesday will showcase brief closing arguments from Jay Sekulow and Pat Cipollone and will take around two hours, according to a person familiar with what we should expect.

Impeachment defense leaves Republican senators little choice

The President and his most fervent fans must have been delighted as they heard arguments that had been rehearsed for months on Fox News opinion shows echo across the Senate floor.

Any vote later this week to depose Bolton or other witnesses could prolong the trial and frustrate Trump's hopes for an acquittal by the time of the State of the Union address next week. It could also expose the minimum of four GOP senators who would be needed to advance such a step to the President's certain wrath.

But most of Trump's lawyers essentially offered Republican senators no choice but to buy the President's case entirely -- despite its many glaring factual deficiencies. For red state senators or those who have concluded their fates lie in sticking closely to Trump, it's an easy political choice.

"The White House counsel has absolutely shredded, shredded, the case brought forward," said Iowa's Sen. Joni Ernst during a dinner break.

Texas' GOP Sen. Ted Cruz added: "I get that the press loves to obsess over the latest bombshell." But, he added, "the legal issue before this Senate is whether a President has the authority to investigate corruption."

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The legal approach pursued by Trump's team leaves moderates such as Collins and Colorado's Sen. Cory Gardner exposed to Democratic claims that they will block a fair trial if they don't vote to hear witnesses such as Bolton.

Trump is being tried in the Senate over two articles of impeachment, alleging abuse of power and obstruction of Congress, in connection with his pressure on Ukraine for an investigation into political opponents including Biden.

In the evening session, Trump lawyer Robert Ray offered a strongly argued case warning about the gravity of removing a President between elections, saying it would not be in the best interests of the country.

"We have witnessed the endless procession of legal theories to sustain this partisan impeachment, from treason to quid pro quo to bribery to extortion to obstruction of justice to soliciting an illegal foreign campaign contribution to a violation of the Impoundment Control Act to who knows what all is next," Ray told senators.

Defense turns into a searing political play

But for much of the day, other members of Trump's team, such as former Florida Attorney General Pam Bondi, offered far more political advocacy.

"We would prefer not to be talking about this," Bondi said, before launching into a fearsome attack on Biden -- an ironic moment, since Trump was the one who had brought up unproven claims about his rival that caused the political drama that has held Washington in thrall for months.

Trump's team even rolled out Bill Clinton nemesis Ken Starr to explode Democratic heads by bemoaning the political damage of an "age of impeachment" -- 20 years after the then-independent counsel had pushed for the 42nd President's ouster.

Ernst seemed to let slip the partisan goal of the defense argument in a conversation with reporters.

"Iowa caucuses are next Monday evening. I am really interested to see how this discussion today informs and influences the Iowa caucus voters, those Democratic caucus voters, will they be supporting Vice President Biden at this point?" she said.

Andrew Bates, a spokesman for Biden's presidential campaign, hit back at Bondi.

"We didn't realize that Breitbart was expanding into Ted Talk knockoffs. Here on planet Earth, the conspiracy theory that Bondi repeated has been conclusively refuted," Bates said. "Joe Biden was instrumental to a bipartisan and international anti-corruption victory. It's no surprise that such a thing is anathema to President Trump."

The President's team argued that he had been right to withhold aid to Ukraine because he feared corruption -- and put Biden and his son Hunter, who was on the board of a Ukrainian energy giant while his father oversaw policy toward Kiev, at the center of the storm.

There is little evidence in the rough transcript of a call between Trump and Ukrainian President Volodymyr Zelensky that Trump was interested in the wider issue of corruption. But he does repeatedly press for probes into Biden.

There are appropriate questions about whether Hunter Biden presented an unacceptable conflict of interest with his employment choices.

But despite Trump's false claims, in fact, Joe Biden's pressure for Ukraine to fire a prosecutor seen in Washington and Europe as corrupt would have made it more likely that Burisma, the company for which Hunter Biden was working, would be investigated.

Still, the President's legal team has the luxury of knowing that its efforts are almost certain to be rewarded given the reality that not enough Republicans will vote to convict their own party's President. That gives them all sorts of leeway to please their boss -- and to advance his political goals.