Could anybody have beaten Marty Walsh this year?

Tito Jackson tried gamely but came within just 31 points in a relative snoozer of a campaign that never truly put Walsh’s second term in jeopardy.

In truth, and in part by design, the mayoralty is designed to discourage the prospect of a viable challenge. No incumbent has lost since 1949.

In interviews, more than a dozen longtime observers of city politics — former officeholders, strategists, business leaders, and elected officials — praised Walsh for his political shrewdness but said incumbency’s clout and his performance had made him all but untouchable after four years.

“It would’ve been pretty difficult to beat him — for anybody,’’ said state Representative Aaron Michlewitz, a North End Democrat who has tangled with Walsh more than once. “I think that speaks to the power of incumbency in the mayor’s seat, but I also think he’s been smart in how he’s operated politically.’’

Among the names mentioned of those who could’ve tested Walsh are the predictable — Walsh’s Lower Mills neighbor state Senator Linda Dorcena Forry, Attorney General Maura Healey of Charlestown, his former rival and onetime city councilor John Connolly, City Council president Michelle Wu, a business-type candidate with deep pockets — and the less politically seasoned.

Think: those with multiple world championships.

David Ortiz? Pros: Equipped with arguably the greatest mayoral campaign slogan of all time, ready-made and expletive included. Cons: Neighborhood coffee hours and parent orientation sessions might not prove sufficiently stimulating.

Tom Brady? Pros: Also decent under pressure, Brady has a proven ability to politick his way around difficult questions. Cons: Has had some presidential political dalliances that might not fly with the city’s progressive electorate. Of course, for Walsh, a longtime Patriots season ticket-holder and Brady idolator, such a matchup could pose emotional as well as political challenges.

Walsh’s true vulnerability, the observers agreed, could have come from the left, particularly from a woman. No woman or person of color has ever been mayor of Boston.

In particular, women of color are ascendant in the city’s politics. Tuesday night’s results landed six women of color on the City Council — the body’s most female members ever and its most councilors of color ever.

“Even the mayor would probably say that if his opponent was Ayanna Pressley, that he would have a tough time,’’ said Joyce Ferriabough, a longtime political consultant.

For Walsh, who beat Connolly in 2013 by appealing to a broad coalition anchored by neighborhoods of color in the geographic center of the city, the vulnerability is clear.

On Tuesday, Wu came within fewer than 6,000 votes of Walsh’s total — in a race against seven other candidates, with voters allotted four votes. The second-place finisher in the at-large race, Pressley, garnered more than 57,000 votes, to Walsh’s haul of more than 71,000.

“This isn’t the ‘New Boston’,’’ said Josiane Martinez, chief executive of the Archipelago Strategies Group, who has advised Walsh, referring to the proliferation of women of color on the council. “This is the ‘New New Boston.’ ’’

Walsh chose to focus his campaign’s energies on confronting President Trump, rather than criticizing Jackson. And he largely succeeded in reprising the coalition that boosted him over Connolly.

Then again, Walsh probably would have been the favorite against any candidate who rose up against him. Incumbency, particularly in Boston, is a nearly impregnable fortress.

He lost just two wards Tuesday, and, facing the most formidable candidate of color since Mel King ran in 1983, captured 80 percent of the precincts of color, according to his campaign. Both wards that Walsh lost — Wards 11 and 12 — lie in the heart of the city.

And Jackson failed to excite an electorate that could have been ripe for a “change’’ election, dissatisfied with the political status quo. Just 27 percent turned out to vote Tuesday.

“It’s one thing to fancy yourself as mayor of Boston,’’ said at-large Councilor Michael F. Flaherty, who won reelection Tuesday and gave Mayor Thomas Menino his stiffest test in 2009 but still fell short by 15 points. “It’s another thing to be mayor of Boston. And I can tell you, firsthand.’’

Sources close to Walsh’s potentially potent challengers — including Healey, Dorcena Forry, and Connolly — say they never seriously considered waging an insurgency. All three backed Walsh.

But that’s not to say Walsh was never vulnerable. An executive who at times is seemingly impulsive, the mayor left himself exposed repeatedly, fumbling the city’s Olympics bid, pushing a race-car event on city streets, and encountering criticism for his response to racial tensions at Boston Latin.

All three rendered Walsh open to attack from the very flank he had sewn up against Connolly — a populist, empathetic approach to city problems that he had experienced himself. In each case, Walsh faced scrutiny because he appeared detached, less in touch with the neighborhoods than with those who have easy access to City Hall.

Jackson, who acknowledged Walsh’s likability in his concession speech Tuesday night, also jabbed at the electoral vulnerabilities he was never able to fully exploit.

Gentrification, displacement, public school funding, and other issues had not been adequately addressed during Walsh’s first term, he said.

“The city of Boston has made some progress,’’ he told supporters at his campaign headquarters after conceding. “It hasn’t made it fast enough.’’

But Jackson also spoke to the campaign’s underlying truth: not that you can’t fight City Hall, but that you can almost never win.

“The mayor of the city of Boston is too strong,’’ he said.

Warren staffs up for 2018

Senator Elizabeth Warren’s state director, Roger Lau, is transitioning out of his government role to take the reins of Warren’s reelection effort.

Lau, who as district director has been Warren’s man-on-the-ground since her first day in office, will be replaced by Nikko Mendoza, communications director at the 1199 SEIU health care workers union, according to people familiar with the plans.

Mendoza, an alumna of both the Menino and Patrick administrations, also worked for Boston 2024, the unsuccessful effort to lure the Olympics.

Lau was Warren’s political director during her 2012 campaign against then-senator Scott Brown, and worked for Hillary Clinton’s 2008 campaign in several states. A longtime aide to then-senator John F. Kerry, he has also worked for, among others, US representatives Michael Capuano, Niki Tsongas, and Richard Neal.

Jim O’Sullivan