(Bloomberg View) -- Hillary Clinton supports adding a publicoption to the Affordable Care Act -- that is, agovernment-run insurance program to compete with private healthinsurance.

She announced her support in July, and the public optionwas the only specific change to Obamacare that she mentioned in hereconomics speech last week.

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This position makes a lot of practical sense, as the NewRepublic’s Brian Beutler has been pointing out. The CongressionalBudget Office has scored a public option as deficit-reducing, whichmeans Democrats wouldn't have to raise taxesor cut spending to pay for it. A public option has also polledwell. For example, back in December 2009 a CBS News/New York Timessurvey found 59 percent favored including a public option inObamacare, with only 29 percent opposed.

It was a big disappointment to liberals during the 2009-2010legislative fight over the ACA when the public option disappearedfrom the bill. So it would seem to be a logical next step forliberal politicians seeking to improve Obamacare.

But it's one thing for Democrats to support a policy. It's quiteanother for it to be the kind of high priority they would fightfor.

Parties have many more goals than they'll ever have theopportunities to enact, even if they win large victories. Gettingbills through Congress is hard, even if majorities in both chambersfavor a measure.

So especially for a major proposal such as the public option,the question isn't whether the party supports it. It's howmuch.

Unfortunately for public-option advocates, the candidates mostlikely to become new Democratic senators in 2017 don't seemespecially interested in advocating that policy.

Only one of 11 candidates, Chris Van Hollen of Maryland,mentions support for a public option on the issues section of hiscampaign website. Indeed, only six of the 11 that I surveyed evenhad a “health care” section on their websites. Kamala Harris, insolidly Democratic California, has nine different subject areas,from immigration to the environment and “protecting animals.” Shehas separate tabs for higher education and K-12 education. But nohealth care.

Sure, given the opportunity, the Democrats might move somerelatively uncontroversial or small health-care measures. But theircampaign messages suggest that they may not be up to a battle overconsequential health-care legislation, which is what a push for apublic option would be.

That doesn't mean it won't happen. Some of these candidateswon’t even be elected. Incumbent senators may have differentpriorities. And some of these candidates may yet add a ringingendorsement of the public option before the election.

But if Democratic party actors were demanding a public option,campaigns would have highlighted it in their campaignmaterials. Indeed, candidates with tough primaries such as KatieMcGinty in Pennsylvania or Patrick Murphy in Florida (whose primaryis still to come), might well have become vocal champions of thepublic option. They didn't.

Campaigns are as much about choosing priorities as they areabout choosing policies. Clinton has clearly committed to adding apublic option to Obamacare -- but she’s also committed to dozens ofother positions. If it isn’t a priority for the rest of the party,it won’t be a priority for her either.

This column does not necessarily reflect the opinion of theeditorial board or Bloomberg LP and its owners.

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