Martin O’Malley Photograph by Gabriella Demczuk / The New York Times / Redux

With all the coverage of Hillary Clinton’s e-mails, another bit of political news has been largely overlooked. At a press conference in Baltimore on Tuesday, Martin O’Malley, the former Democratic governor of Maryland, said that he won’t seek the U.S. Senate seat that Barbara Mikulski, Maryland’s five-term Democratic senator, has announced she will vacate in 2016. Rather than entering a Senate race in which he would immediately be the favorite, O’Malley appears set to go all-in and challenge Clinton for the Democratic Presidential nomination.

Officially, O’Malley is still merely considering a bid. But his travel schedule suggests otherwise. Last weekend, he was in South Carolina; this weekend he’s headed to New Hampshire. He has also scheduled trips to Iowa this month and next.

If O’Malley does formally enter the race, he’ll be a heavy underdog, of course. Still, he’ll find some encouragement from Clinton’s ongoing troubles. On Wednesday, the Associated Press reported that she maintained her own home-brew server for the private e-mail address that she has been revealed to have used for work correspondence as Secretary of State, rather than relying on an outside service, such as Google or Yahoo. “Operating her own server would have afforded Clinton additional legal opportunities to block government or private subpoenas in criminal, administrative or civil cases because her lawyers could object in court before being forced to turn over any emails,” the A.P. story said.

Yesterday, I expressed some skepticism about whether the e-mail flap would amount to much over the long term, and about whether the Republicans would be able to use it against Clinton once the campaign proper starts. In seeking to keep her State Department e-mails from prying eyes, she clearly skirted the rules. But it appears that she didn’t break the federal recordkeeping laws in place at the time, and everyone knows that she has good reason to be paranoid: on Capitol Hill and elsewhere, many people are out to get her, Republican attack dogs prominent among them.

The danger to Clinton is cumulative and close to home. In the past few weeks, many Democrats, particularly those on the progressive wing of the party, have been reminded of their reservations about a Clinton restoration. To begin with, there was the spectacle of Hillary, fresh from the State Department, traipsing around the country making highly paid speeches to Goldman Sachs, the Carlyle Group and other redoubts of the one per cent. Last week came the revelation that foreign governments were making financial contributions to the Clinton Foundation while Hillary was still serving as Secretary of State. And now there’s her e-mail system, which appears to have been explicitly designed to frustrate legitimate requests for documents from the media and from Congress. It all adds to the impression that the Clintons operate by their own set of rules.

So far, other potential Democratic challengers, who include Vice President Joe Biden and Jim Webb, the former senator from Virginia, have shied away from criticizing Hillary directly, but this may be about to change. During O’Malley’s recent trip to South Carolina, the Associated Press reported, he “took a veiled shot at Clinton, warning Democrats that more ‘triangulation’ would not be a successful strategy for the party.”

The reference, to Dick Morris’s term describing Bill Clinton’s strategy for transcending ideological polarities, hardly constituted a venomous attack. O’Malley, who began his career in politics by working for Gary Hart’s 1984 Presidential campaign, is a thoughtful and deliberate politician, rather than a showman or a brawler. His standing in Democratic politics is currently diminished, however, by the results of last November’s gubernatorial election, in which O’Malley’s chosen successor, his lieutenant governor, Anthony Brown, suffered an upset defeat to the Republican candidate, Larry Hogan.

O’Malley had a strong record as governor, promoting the use of information technology, seeing liberal measures on immigration and gay marriage into law, and repealing the death penalty for future offenders. In recent months, he has been reaching out to progressives in the early primary states, and echoing many of the themes that made Massachusetts Senator Elizabeth Warren popular, such as calling for the break-up of big banks. ”People want to see new faces,” Dan Calegari, a Democratic activist in New Hampshire, told the A.P. “There’s a certain amount of Clinton fatigue. They’ve been around for thirty years now. Quite honestly, I think if Martin decides to get in the race, he will surprise some people.”

To repeat, O’Malley would be a long shot. British bookmakers currently have the odds that he will win the nomination set at around twenty-five-to-one. Warren, despite her protestations that she won’t run, is at seven-to-one. Biden is at sixteen-to-one. Clinton remains the favorite, of course, but the betting markets suggest that the race isn’t entirely sewn up. At most of the bookmakers, the odds on her emerging as the Democratic candidate are one-to-three, which means that you would have to put down three dollars to win one dollar. These numbers imply that there’s a seventy-five-per-cent probability that Clinton will get the nomination. Until now, most political operatives and pundits, myself included, have been tacitly assuming that the chances that Hillary won’t be the Democratic candidate were lower than one in four. It may be time for a reassessment.