(CNN) Impeachment was meant to punish Donald Trump's unrestrained use of his authority , but the grounds on which Republican senators plan to acquit him may instead give him a green light to use his power however he wants to win reelection.

Trump's GOP defenders looking to end his Senate trial in the next few days are increasingly arguing that it's time to shut things down because even if Trump is guilty of coercing Ukraine for political favors , such conduct would not be impeachable.

They are seizing on stunning arguments envisioning almost unchallenged presidential power and highly limited criteria for defining the abuse of power and impeachment laid out by a maverick member of Trump's legal team, Harvard Law professor Alan Dershowitz

Republican leaders are meanwhile increasingly confident they will have the votes to block Democratic demands for the testimony of new trial witnesses, including John Bolton, who reportedly has information implicating Trump in pressuring Ukraine for political favors.

The quickening bid to squelch any further fact-finding in the trial is also taking place as the White House seeks to delay publication of the former national security adviser's forthcoming book, which The New York Times has reported to be deeply critical of Trump's behavior towards the Kiev government and elsewhere.

The Senate impeachment trial resumed on Wednesday for the first of two days of questioning from senators to the Democratic House impeachment managers and the President's lawyers.

Developments on multiple fronts -- apparently trending favorably for the President -- come as GOP senators coalesce around a narrative that would set a breathtaking new standard for presidential power.

"For the sake of argument, one could assume everything attributable to John Bolton is accurate and still the House case would fall well below the standards to remove a president from office," South Carolina Sen. Lindsey Graham said in what his office says is his definitive impeachment statement.

Sen John Barrasso, a member of the GOP Senate leadership, added: "Even if everything in the book is true, it doesn't rise to the level of impeachment."

And Sen. Mike Braun of Indiana said: "It's not even getting close to getting something that's impeachable."

The implication of such an approach is that leaning on a foreign nation for dirt on a political opponent is not an abuse of power or impeachable offense and is also a perfectly permissible use of the authority that comes with the President's office. That could have huge implications for the coming election and for the way future presidents use their power to further their political ends.

Acquitting Trump on such grounds could also open the door to foreign nations keen to see him stay in office to offer political dirt in return for inducements that could be retrograde to US national interests and that effectively amount to interfering in American elections.

It might leave Trump -- whose presidency has been marked by repeated power grabs -- wondering what is to stop him from using every instrument of his power to ensure victory in November. And if the argument is enshrined as precedent by a vote to acquit Trump it could mark a huge enhancement of presidential power -- by half of a branch of government, Congress -- constitutionally charged with checking the executive.

In other words, Trump could emerge from his impeachment scrape with his power enhanced.

Changing rationale for acquittal

Republicans have variously argued that Trump did nothing wrong, the Democrats made up impeachment charges or that there was no quid pro quo in Ukraine. But they have apparently been pushed to this final, fallback position in the light of Bolton's claim in a manuscript for his new book first reported by The New York Times that Trump did indeed tell him to withhold aid to Kiev until it opened probes into his domestic foes.

The legal reasoning from Dershowitz -- while outside the mainstream -- is giving Republican senators political cover to stand with the President.

The Harvard emeritus professor claimed on the Senate floor that if a politician thinks his reelection is in the national interest, any actions he takes towards that end cannot by definition be impeachable.

"And if a president did something that he believes will help him get elected, in the public interest, that cannot be the kind of quid pro quo that results in impeachment," Dershowitz argued.

Lead House impeachment manager Adam Schiff however argued that such a position suggested an interpretation of the Constitution that held it acceptable for a President to abuse his power and Congress could do nothing about it.

"You can't do anything about it because if he views it as in his personal interest, that's just fine. He's allowed to do it. None of the founders would have accepted that kind of reasoning," Schiff said, adding later, "In fact, the idea that the core offense that the founders protected against, that core offense is abuse of power, is beyond the reach of Congress through impeachment would have terrified the founders."

CNN legal expert Carrie Cordero said that Dershowitz's arguments -- that CNN reporters in the chamber said were warmly received by Republican senators -- were nonsensical.

"It basically means that a President can do anything and they can make a subjective determination that their reelection is in the national interest," Cordero said.

"It invites and opens the door to anything that is in the realm of foreign influence."

Dershowitz reacted angrily later on in the question-and-answer session to suggestions by the House impeachment managers that he was in a slim minority of legal thought, claiming that constitutional experts who did not agree with him treated Republican and Democratic presidents by different legal standards.

"These scholars are influenced by their own bias, by their own politics and their views should be taken with that in mind. They simply do not give objective assessments of the constitutional history," Dershowitz said.

The spectacle of Republicans adopting such arguments is remarkable since the party that once saw itself as the epitome of limited government is coalescing in an effort to broaden the unrestrainable power of the presidency. But it is also thematically compatible with the idea of a "unitary executive" -- a theory that grants expansive powers to the presidency and is advanced by some conservative lawyers -- including current Attorney General William Barr. In his own way, Trump has argued similar points, claiming that Article II of the Constitution gives him the power to do anything he wants.

New energy in the chamber

The question and answer session transformed the hitherto sleepy atmosphere in the Senate. Instead of enduring hours of legal arguments, senators acting as jurors got to play a role -- and many appeared to be jotting down questions on the fly and sending them to Chief Justice John Roberts to read out

Each legal team was allotted five minutes to answer each question, meaning that the day -- that unfolded almost like a law school seminar -- unfolded at a sprightly pace.

The most interesting question may have been the first -- lodged by Sen. Susan Collins of Maine on behalf of Alaska Sen. Lisa Murkowski and Utah's Mitt Romney -- a trio seen as most likely to defy GOP leaders and vote to hear the testimony of Bolton and other witnesses.

Collins asked the President's defense team whether senators should consider whether the President had multiple motives -- not just seeking political gain -- for holding back nearly $400 million in military aid from Ukraine and whether it would make a difference to the impeachment case.

"If there is any possibility, if there is something that shows a possible public interest and the President could have that possible public interest motive — that destroys their case," said deputy White House counsel Patrick Philbin.

The question from Collins stirred immediate interest in the chamber and speculation outside as to whether she was seeking a rationale to explain any decision to vote against hearing witnesses.

But Schiff turned the question to his own advantage, answering that uncertainty about the President's motivation could easily be cleared up -- by hearing from Bolton.

"It makes it all the more essential to call the man who spoke directly with the President, that the President confided in and said he was holding up this aid because he wanted Ukraine to conduct these political investigations that would help in the next election," Schiff said. "Don't wait for the book."

In another significant development on Wednesday, Republican Sen. Cory Gardner of Colorado announced that he would vote against any attempt to call new witnesses.

The swing state senator has been in a tough spot as perhaps the most vulnerable Republican seeking reelection in the fall. His decision reflects the fact that while more moderate voters critical of the President may disapprove of Gardner standing with the President -- he has little chance of reelection without Trump's fervent political base.