Martin O'Malley's presidential bid: Would it hurt Hillary, or help her?

Former Maryland Gov. Martin O'Malley, who is reportedly planning to announce his candidacy for president, could serve as a foil for Hillary Clinton, helping to better define her campaign.

It's (almost) official: Martin O'Malley will run for president.

The former Maryland governor plans to announce May 30 in Baltimore, according to reports.  Almost immediately, the chatter about his not-yet-announced candidacy isn't about him, it's about Hillary Clinton.

What will Mr. O'Malley's run mean for a Clinton candidacy? Will it push her to the left? Will it hurt her? Or could it possibly help?

Like a younger sibling who can't escape the shadow of his scene-stealing elder, O'Malley has gone to lengths to distance himself from the Democratic frontrunner, casting himself as the progressive alternative, the anti-Hillary.

In so doing, O'Malley, the former Maryland governor, has co-opted a central theme of Massachusetts Sen. Elizabeth Warren's pitch. Progressives who see Clinton as a centrist beholden to Washington and Wall Street have been badgering Senator Warren to run for months. As the chances dim that the liberal hero will run, O'Malley has stepped in to assume the progressive mantle.

“O’Malley’s operation sees that Warren isn’t running and that her progressive supporters can be persuaded to support him,” a Democratic operative told Politico. “If he does become a real candidate he can have more direct influence over Hillary than Warren. That seems to be his pitch these days.”

In fact, O'Malley met with about 30 progressive leaders and academics in New York earlier this week, according to reports, a sort of "happy hour/pow wow with lefty leaders and operatives to show he is a serious contender for 2016."

He's also echoed that progressive theme in his proposed policy agenda, suggesting he would work on economic inequality, campaign finance reform, and building alliances overseas.

One possible effect: If his vision attracts enough support, O'Malley may succeed in pushing Clinton to the left – a phenomenon that has been mirrored in recent Republican nominating races.

He may also give Clinton some much-needed competition, and along the way, inadvertently help her. 

"Clinton needs a foil in the Democratic primaries—someone she can joust with, someone who will expand the narrative, and someone she can beat," writes Mother Jones' David Corn. "A fight or, at least, a tussle—even a lopsided one—will give her campaign more of a story to tell, and, presuming she wins the primaries, will position her as, well, a winner, not a candidate who is skating toward the general election on the easy ice of entitlement and inevitability."

Of course, O'Malley isn't running to help Hillary – he's running to beat her.

Which is why the former governor, known for his low-key style, has recently donned his boxing gloves.

"Let's be honest here," O'Malley said during a March 29 appearance on ABC’s “This Week." "The presidency of the United States is not some crown to be passed between two families."

There's bite behind his bark. O'Malley was mayor of Baltimore and a two-term governor of Maryland, where he built a strong liberal record by tightening gun control, legalizing same-sex marriage, abolishing the death penalty, and working toward legalizing marijuana. O'Malley has faced criticism following the Baltimore riots because his "tough-on-crime" policies while mayor from 1999 to 2007 led to what minorities see as rampant racial bias in policing in the city, potentially a liability among his liberal base.

Though he's no Clinton, his fundraising capabilities and party contacts arguably surpass that of his potential rivals like Vermont Sen. Bernie Sanders and former Virginia Sen. Jim Webb.

But, again, the magic words – he's no Clinton. His name recognition is abysmal, as is his polling.

In early presidential polls, Clinton typically polls more than 60 percent. O’Malley? He's doing well if he's above 2 percent.

O'Malley, for his part, appears prepared to take on the Clinton machine.

Recalling the 2008 Democratic primary, when Clinton was ousted by another unlikely contender, he told ABC, "History is full of times when the inevitable frontrunner is inevitable right up until he or she is no longer inevitable."