A key swing vote on healthcare reform hinted Wednesday morning he might support a public option if reforms to the private insurance market fail.

Sen. Evan Bayh's (D-Ind.) argument is that the government ought to use anti-trust laws to create competition and drive down healthcare premiums. If those rules insufficiently address the inequalities in the insurance market, however, he suggested the next step should be a government intervention.

"I've had an open mind on [the public option] from the beginning, and I still do," Bayh told MSNBC, adding that the goal -- no matter what the tactic -- was a fair and efficient free market.

But, Bayh added, "From time to time, when there's problem with that, if you have something called a 'natural monopoly,' well then the government steps in to regulate that, to make sure they don't gouge consumers. And if you have to use the anti-trust laws or other steps to make sure there's robust competition, that people get the choices and the lower costs they deserve, you use the law for that purpose."

Only if those reforms failed, Bayh explained, should the government create its own plan to compete in the private sphere. His stance, interestingly enough, is not too unlike the public option "trigger," which would institute a government plan if private insurers failed to meet coverage and cost benchmarks by a specified deadline.

"I think we ought to try first aggressive market reforms to get that competition and lower prices the American people want. I think that's what the president was alluding to in his speech," Bayh said. "If that does not work, well then there's an appropriate role for government to step in. But that should be, not the first choice, that should be only if the free market cannot be reformed sufficiently."