Rick Hampson

USA TODAY

NEW YORK — “Great men have big failures,’’ Rudolph Giuliani has said of Donald Trump’s business career. But the hero of 9/11, known once as “America’s Mayor’’ and now as Trump’s most dogged surrogate, could say the same of his own career, which has as many ups and downs as the skyline.

It’s a matter of opinion where Giuliani’s latest iteration moves this erratic trajectory, but it cements his status as the Jekyll and Hyde of U.S. politics.

Fifteen years ago, Americans watched as Giuliani, cool and courageous in the dust of the World Trade Center, consoled the bereaved and encouraged the frightened. TIME named him Man of the Year.

This year they’ve seen a different Giuliani — wide-eyed and high-pitched, hyperbolic and hyper-partisan, sometimes out-Trumping the GOP presidential nominee himself.

That Giuliani was on display last weekend. As Republicans from Trump’s running mate on down distanced themselves from his bragging about sexual aggression toward women in a 2005 recording, Giuliani filled the breach.

Giuliani hits the airwaves to defend Trump

On Saturday, Giuliani said that Republicans who want Trump to resign from the ticket were against him from the start, and that “If you want change in Washington, you vote for Donald Trump.’’

The next day, several Trump surrogates cancelled appearances on news talk shows. Giuliani went on. "Men at times talk like that,'' he told CNN, referring to Trump. The next day, at a rally in a sports area, he jokingly alluded to Trump's defense that his 2005 comments were merely "locker room talk.'' Giuliani said the Clinton Foundation's fundraising "is as phony as — I can't say the word, because I have to be nice. I might say it back in the locker room.'' The crowd roared.

“Rudy seems more into Trump’s presidential campaign than he was into his own’’ in 2008, says Wayne Barrett, an investigative reporter who’s followed Trump and Giuliani for years. “Even when he’s got limited material, he knows how to argue a case.’’

Better, sometimes, than the candidate himself. “Rudy is so much more articulate than Trump,’’ says Fred Siegel, a former Giuliani adviser and biographer. “He’s a better spokesman for Trump than Trump.‘’

But Giuliani has supported abortion rights, immigration and an assault weapons ban. Is his crusade for Trump tarnishing his reputation?

“I don’t think he’s helping himself,’’ says Siegel. “His performance at the convention was so over the top. (Giuliani: “There’s no next election! This is it!’’) People I know who are pro-Rudy were stunned, scratching their heads. It was operatic.’’

Whatever its impact on his national image, Barrett says, Giuliani’s support of Trump “hurts him in New York,’’ where Hillary Clinton is expected to win overwhelmingly. “This is his home. These are the circles in which he moves.’’

Evidence of that tension surfaced last week when the New York law firm that Giuliani joined in January announced he’d take a leave of absence until after the campaign. Giuliani said he agreed with the move, but the New York Observer — published by Trump's son-in-law, Jared Kushner — reported that “the move was not voluntary on Rudy's part’’ and cited a firm source that Giuliani “was strongly encouraged to take this action as the presidential campaign grows ever more heated.'''

Giuliani takes leave of absence from job, all in for Trump

Rudy on love and war

Giuliani’s advocacy of Trump has at times been clumsy.

He claimed that there were no terrorist attacks on President George W. Bush’s watch (forgetting 9/11) and that Trump had recanted his claim that Barack Obama was not a U.S. citizen (when Trump had not). He defended Trump’s argument that the U.S. should have taken Iraq's oil after the 2003 invasion by saying, "Until the war is over, anything's legal.’’

He said a Trump speech in August was “the best speech any Republican, at the least, has ever given,’’ apparently including those by Lincoln and Reagan. When reminded, during a discussion of Bill and Hillary Clinton’s marriage, that he himself faced charges of marital infidelity, Giuliani responded, “Well, everybody does.’’

Giuliani: Lewinsky shows Clinton 'too stupid to be president'

Giuliani blasts Clinton, touts Trump for American security

He also said, referring to Trump, that “a man who has this kind of economic genius is a lot better for the United States than a woman, and the only thing she’s ever produced is a lot of work for the FBI checking out her emails.”

None of these gaffes rule Giuliani out of the Surrogates Hall of Fame. Presumably, he prefers the Gettysburg Address to any of Trump's, and hasn't forgotten what year 9/11 occurred. As for infidelity, he later said he was talking about infidelity in general — lies and other sins.

But these miscues create the impression of a supposed wordsmith — best-selling author, popular lecturer — off his game, at minimum. Barrett, no admirer, says he's sometimes looked “unhinged.’’

In fact, Barrett and Siegel (who calls Giuliani the city’s greatest mayor) agree that he isn’t much of a politician. In Giuliani’s 2008 bid for the GOP nomination, Siegel recalls, “he started out in the stratosphere. The more he campaigned, the worse things got.’’ He spent $65 million and won not a single convention delegate.

The three apologios

Giuliani is one of three key Trump surrogates. Politically, all have seen better days.

Chris Christie

Once the hope of moderate Northeastern Republicans, the New Jersey governor ended a disastrous presidential campaign after coming in sixth in the New Hampshire primary.

This fall he's been the off-stage villain at the trial of two former aides accused of blocking George Washington Bridge traffic to punish a political opponent. The only thing the prosecution and defense agree on is that, despite his denials, Christie knew what was going on.

Newt Gingrich

The former House speaker has baggage of his own. He was summarily deposed by his colleagues as speaker 17 years ago. Like Trump and Giuliani, he is on his third marriage — a handicap when asked to talk about the Clintons’ 41-year marriage.

Lately, Gingrich has been straying off message. He told Fox News host Sean Hannity that the end of September was a “lost week’’ for Trump that “has shaken his own supporters.’’

Of the three, Giuliani may have the most to offer, most to gain and least to lose. “His reputation is pretty much set in stone, no matter what happens,’’ says Brigid Harrison, a political analyst who teaches at Montclair State University in northern New Jersey.

She says the three surrogates are crucial because, unlike most nominees, Trump does not have lots of senators and governors working for him in their states. Wisconsin Gov. Scott Walker “would be an articulate surrogate,’’ Siegel says, “if he didn’t hate Trump’s guts.’’

Giuliani plays another role in the campaign: adviser. He reportedly urged Trump to tone down his rhetoric, reach out to African Americans and press the crime issue. He attended and spoke up at Trump’s first national security briefing as a presidential nominee and his meeting with Mexican officials.

Giuliani’s motives have been subject of much speculation. Supporters say he’s helping an old friend (Trump, whose last wedding he attended and whose father he eulogized); hurting an old enemy (Clinton, whom he almost opposed for U.S. Senate in 2000 until he was diagnosed with prostate cancer); and shaping a presidential campaign — and potentially a presidency.

“He adds policy heft, especially on homeland security and crime,’’ Siegel says. “And he’s a top-notch manager.’’ Even if Trump loses, and if President Clinton falters, “He can say, ‘I told you so!’’’

Is it Trump or Clinton?

2016 Poll Tracker - USA TODAY

Despite handwringing about Trump’s damage to Giuliani’s reputation, the latter’s legacy was complicated to begin with.

Giuliani has been, in succession, a mob-busting federal prosecutor; an unsuccessful mayoral candidate; a mayor widely credited with making New York City livable again and widely scorned as a flagrant adulterer; a leader who failed to anticipate the 2001 terror attack, who performed brilliantly in its aftermath, and who tried unsuccessfully to stay in office after his term expired; and a terrible presidential candidate.

For years, he’s muddied his old non-partisan image. Last year, for instance, he said he doesn’t believe President Obama loves America.

At the end of World War II, an editor gave this advice to Winston Churchill (whose checkered career Giuliani compares to Trump’s): Run non-partisan in the next election rather than as head of the Conservative Party, and retire shortly thereafter.

Churchill refused. “I fight for my corner,’’ he said. And “I leave when the pub closes.’’

This year, Rudy Giuliani fights for his corner. And the pub is still open.