(CNN) When Republican Rep. Michael Grimm resigned from Congress in early 2015 after pleading guilty to tax evasion, his political future looked sealed -- over and done, the former Marine and FBI agent a liability the party was desperate to get out of the headlines.

But as New York Republicans head to the polls on Tuesday, Grimm, who has led Rep. Dan Donovan in the little reputable polling that's available, looks to have a real chance of winning the GOP nomination and a shot at reclaiming his old seat.

A victory in the primary for Grimm, a little more than two years after his release from prison, would be a Trump-era fairy tale -- proof again that in the current political landscape, the standards and expectations for those in power are constantly being rewritten.

For his part, President Donald Trump is backing the incumbent Donovan. Trump endorsed the former Staten Island district attorney in a pair of tweets late last month. One warned that Grimm, like Roy Moore in Alabama, would be deadweight in a general election. Undeterred, Grimm has carried on, uncompromising in his support for the President, with Trump loyalists like Michael Caputo, a longtime GOP operative, and Anthony Scaramucci, the briefly tenured White House communications director, in his corner.

Former New York City Mayor Rudy Giuliani, now Trump's lawyer, has stumped for Donovan.

The candidates' jockeying to appear the closer one to Trump has created more than a few odd spectacles. Grimm relishes -- and has sought to prop up -- the perception that he is Trump's political kin, with Donovan standing by as the face of the GOP old guard. Grimm aligned himself with Steve Bannon early in the campaign, then shrugged him off when the former Trump aide ran afoul of the White House. Grimm also has passed out campaign placards that read "Grimm 2018" on one side and "Trump 2020" on the other.

He has sought to embed his own history of legal trouble into conservative anger over the probe into Russian election meddling and the Trump campaign's potential entanglements.

Like with his prosecution, Grimm alleges, Trump is being targeted by biased law enforcement leaders. Grimm has claimed in the past, and maintains to this day, that he was tipped off during his time in office that "a deal was made with (then-US Attorney Loretta Lynch) that she would be put at the top of the shortlist for (US attorney general) if she took me down."

Asked last month why he, of all people, had been targeted, Grimm told CNN in an interview, "Well, how about the fact that I was the only federally elected Republican in the entire city of New York? So that's one good reason. Second, I was rising like a rocket."

The record suggests something less sinister. A probe into Grimm's fundraising eventually led prosecutors to file a 20-count indictment in April 2014, with charges including conspiracy to defraud the United States, wire fraud and hiring undocumented immigrants.

Grimm, who was re-elected in November 2014 during the course of his legal battle, ultimately pleaded guilty to one count of tax evasion. He announced plans to resign before the end of the year. Now, though, he is attempting to parlay his prosecution into a political coup -- just another proof point that he can be counted on to stand by Trump in Washington.

"I will bet you that I will have more than 80% of retired cops in this district will vote for me," Grimm said last month, casting his crime -- "three delivery boys (paid) off the books" -- as overblown. "I should have been given a civil fine. The hardworking people here in Staten Island, they all know I got screwed."

At a rally there in mid-May, Caputo, the former Trump campaign adviser helping Grimm, neatly summed up his candidate's case.

"I think that when we elect Michael Grimm here, we'll be able to prove to these people who are weaponizing the DOJ and all of its bodies that the people aren't standing for it anymore," Caputo said. "In my mind, this is a battle for the President. Not just because somebody supports the President, somebody doesn't, but the entrenched political interests who targeted and went after Michael Grimm are ones who went after and targeted the President."

An enduring affection for Grimm is evident on Staten Island. As a lawmaker in the old GOP minority, he worked across the aisle, passing up a place in the tea party caucus after being elected in 2010 and instead entering the ranks of the more moderate Republican Main Street caucus, and he even cosponsored popular flood insurance legislation with Democratic Rep. Maxine Waters of California.

His supporters are quick to highlight his tireless work in the aftermath of Hurricane Sandy in 2012. And they generally recall his infamous threat to throw a reporter off a balcony -- caught on camera -- and "break (him) in half, like a boy," as a forgivable lapse. Grimm apologized then and, even today, remains somewhat sheepish when recalling the scene.

Donovan is betting that Grimm's past, weaved in with Trump's support, will be enough to break those old bonds for good and convince voters that a felon with a temper isn't fit to carry the GOP banner in November. In a debate last week, their second heated one-on-one in the space of a few days, Donovan alleged that Grimm used his House seat as leverage, back in 2014, when it became clear federal prosecutors had him pinned.

"My opponent lied to our community, asked us to vote for him and then used our vote to cut a deal with the Justice Department, to get a sweeter deal," Donovan said. "And we didn't have a voice in Washington for over five months," from the time of Grimm's resignation until the special election to replace him.

Donovan also mocked Grimm's support for mandatory E-verify legislation, which would require employers confirm that potential hires are documented.

"If we had E-verify when (Grimm) owned his restaurant," Donovan said, "he would have been caught a lot earlier."

Like Grimm, Donovan has gone to significant -- sometimes overcooked -- lengths to demonstrate his devotion to Trump. He frequently touts their personal relationship and in April introduced legislation to "require the United States Postal Service to display the official portrait of the incumbent President and Vice President in all post offices."

Trump has returned the love, tweeting his endorsement on May 30, saying Donovan is "strong on Borders & Crime, loves our Military & our Vets, voted for Tax Cuts and is helping me to Make America Great Again."

Donovan did not, in fact, vote for the GOP tax bill, but Trump's angle -- and his worry -- were made clear in a subsequent post, when he compared Grimm's candidacy to Moore's disastrous Senate bid.

"Very importantly, @RepDanDonovan will win for the Republicans in November...and his opponent will not," the President tweeted . "Remember Alabama. We can't take any chances on losing to a Nancy Pelosi controlled Democrat!"

At a recent rally, Giuliani accused Grimm of using the campaign as a means of personal gain -- an angle to shed his criminal record.