Martin O'Malley insists Hillary Clinton is not the 'inevitable frontrunner' in 2016
Former Democratic Maryland Governor Martin O'Malley in Washington, DC, on March 10, 2015 (AFP Photo/Jim Watson)

Hillary Clinton may be the presumptive Democratic frontrunner in the 2016 presidential race, but she is by no means the party's "inevitable" nominee, a likely challenger said Thursday.

"Maybe that's the way it is today," former Maryland governor Martin O'Malley acknowledged on MSNBC's "Morning Joe" program.

"Most years there is the inevitable frontrunner. And that inevitable frontrunner is inevitable right up until he or she is no longer inevitable," he added.

The timing of O'Malley's jab is notable. Clinton is embroiled in controversy about her use of a private email account for her entire four years as secretary of state, and her Tuesday press conference did little to quell the furor.

A New York Times report Thursday said congressional Democrats were nevertheless desperate for Hillary to run in 2016, saying she is "simply too big to fail."

While Clinton tops all polls on who Democrats would pick for president, O'Malley countered the notion that the most powerful woman in American politics was a lock for the nomination.

And he stressed that if he threw his hat in the ring, he would not be aiming for a consolation prize, such as the vice presidency or a cabinet post.

"I would be running not only to win but to govern well, to make the case to the people of the country there are better choices we can make together that will make wages go up and to make college more affordable for our kids again," O'Malley said.

He said he expected a "robust conversation" among Democrats during the campaign.

But O'Malley appeared unwilling to unsheathe the knives just yet, declining to say whether Clinton did anything wrong in her email kerfuffle.

He said he will announce his political intentions this spring. Clinton observers expect her to do the same.

Last week, when Maryland's long-serving Senator Barbara Mikulski announced she would not seek re-election in 2016, instead of jumping into the battle to replace her, O'Malley begged off.

Still, he has a long way to go -- on the calendar and in polls.

An NBC survey this week showed Clinton with 86 percent support, versus just 11 percent for O'Malley.

"Am I really up to 11 percent?" he asked with a grin.