Longshot presidential candidate Martin O'Malley has failed to submit enough valid signatures to participate in the Ohio Democratic primary ballot this March, state officials said Thursday.

According to the Baltimore Sun, the former Maryland governor submitted 1,175 signatures to the Ohio secretary of state, 175 more than the minimum requirement. However, a secretary spokeswoman said only 772 of the signatures were valid.

The news marks a major setback in O'Malley's campaign, which has failed to gain recognition among voters and the media. With only a month left before primary voting begins, this may be the nail in the coffin for the underdog candidate.

Democratic rivals Hillary Clinton and Bernie Sanders both managed to surpass the 1,000-signature requirement to compete in the swing state, where victory often proves crucial in winning the primary, and eventually the White House.

Larry J. Sabato, director of the Center for Politics at the University of Virginia, said the development was a "disaster" for O'Malley, but ultimately didn't make much of a difference to the presidential race as a whole.

"Let's not oversell it," Sabato said. "I don't know anyone who takes Martin O'Malley's candidacy seriously at this point. He was long ago eclipsed by Bernie Sanders as Hillary Clinton's main challenger. He's done nothing to change that."

Despite having relative success in his debate appearances, O'Malley's poll numbers have not exceeded 10 percent in any state.

O'Malley's campaign expressed disappointment at the turn of events, but they did not throw in the towel.

"While this news is disappointing, we are exploring all of our options, and Gov. O'Malley will campaign vigorously in Ohio," spokeswoman Haley Morris said to NBC News.

Veteran Democratic campaign strategist Joe Trippi said that if O'Malley was to experience a surge in the polls, it's not inconceivable that he could win without being on the Ohio ballot. For instance, delegates pledged to another candidate could choose to support O'Malley instead.

"It's unlikely he's going to take off, but if he does, that's not an unsurmountable problem," Trippi said. "This game's been played before. This is a problem that has happened many, many, many times. If you're in it, there are a ways to get around the problem."