Let the 2016 Senate sweepstakes begin, although this one may have more impact on the presidential race. Barbara Mikulski, the Maryland Democrat serving her sixth term in the Senate, announced earlier today that she will not run for re-election in 2016. The former Appropriations chair’s retirement will force Democrats to defend an extra open seat — or will it provide an opportunity to clear the field for a coronation?

Mikulski, whose direct and feisty character paved the way for women who joined the Senate, joined the Senate in 1987 after ten years in the US House. The 78-year old intends to serve out the remainder of her current term until January 2017.

In any other profession, retirement at Mikulski’s age would be expected. At 78, though, there are plenty of other incumbents who would be planning the next campaign. The Maryland seat would be tough for Democrats to lose, but they thought the same thing about the governor’s office after Martin O’Malley, and they lost it by ten points. At a minimum, Mikulski’s retirement forces Maryland Democrats to focus on the Senate race rather than the presidential race, and it might require some help from national Democratic orgs to keep the Senate seat in their hands. That’s efforts that could detract from helping the national ticket, too.

Speaking of which, the Washington Post says this will result in a “wild primary” for Maryland Democrats to fill the slot. It might make the presidential primary a little less wild for Democrats, though:

Her retirement is expected to spark a wild primary on the Democratic side, with several of the seven Maryland Democrats in Congress taking a look at the race, including Reps. Chris Van Hollen, Elijah Cummings, Donna Edwards, John Delaney and possibly Rep. John Sarbanes, whose father also served in the Senate.

The race could also be tempting for former governor Martin O’Malley, who is weighing a 2016 presidential bid that has yet to get any traction. O’Malley, however, has served in an executive role for the past 15 years, a stint that includes his tenure as Baltimore mayor, and advisers have previously said he has limited appetite for legislative service.

O’Malley often gets mentioned as an alternative to Hillary Clinton’s expected coronation for the 2016 nomination, but the loss of his handpicked successor seemed to have damaged that perception. He’s close to the only legitimate alternative Democrats have from their gubernatorial ranks to Hillary, but he hasn’t got the national draw of the Clintons, nor the charm and novelty of a Barack Obama. A longtime reporter from Maryland told me last week that he believes O’Malley’s charisma has been seriously underestimated, though, and could present a problem for Hillary if he decided to get serious about a presidential bid.

Mikulski’s retirement might solve that problem for Democrats. If O’Malley runs for the US Senate now and Hillary somehow won in 2016, he’d be just 61 years old in 2024 to make another run at the big brass ring from Capitol Hill. If she lost, he’d be in position to run in 2020 at 57 years old. That would bring an end to O’Malley’s potshots from the sidelines at Hillary (via Legal Insurrection’s William Jacobson):

Martin O’Malley, the former Maryland governor who is likely to seek the Democratic nomination for president in 2016, took a veiled shot at a potential rival, Hillary Rodham Clinton, in a speech in South Carolina on Saturday, criticizing the politics of “triangulation” that have historically been associated with the Clintons.

“The most fundamental power of our party and our country is the power of our moral principles,” Mr. O’Malley said, according to a transcript of his remarks provided by an aide.

In words that echoed those of Senator Barack Obama when he battled Mrs. Clinton in 2007 for the Democratic nomination, Mr. O’Malley added: “Triangulation is not a strategy that will move America forward. History celebrates profiles in courage, not profiles in convenience.”

O’Malley may not win a Senate seat without any challenges, especially given how the blue state went red last November, but he’ll have much better odds of taking it than he will of beating Hillary Clinton to the finish line for the presidential nomination. This is a deal just begging Democrats to be made.

Update: Mikulski is serving her fifth term in the Senate, not her sixth. I’ve corrected the headline and the post.