LANSING, Mich. (AP) — A Democratic activist has asked a federal court to halt Michigan's Democratic presidential primary, saying it will disenfranchise voters whose favorites aren't on the ballot.

Martha Hayes' suit against the Michigan Democratic Party, the state of Michigan and Secretary of State Terri Lynn Land asks the court for both preliminary and permanent injunctions.

If successful, it could force Michigan Democrats to hold a presidential caucus, something some Democratic activists already think is a good idea.

Michigan Democratic Party spokesman Jason Moon didn't seem too concerned Tuesday that the primary was in trouble.

"We think this lawsuit is meritless," he said.

The suit was filed late Monday afternoon in the U.S. District Court in Grand Rapids by Grand Rapids attorney Earl Erland, a supporter of Democratic presidential candidate John Edwards.

It says Democratic activists' rights to campaign for a candidate and make a meaningful choice is being hampered because four candidates are not on the ballot. Edwards, Barack Obama, Bill Richardson and Joe Biden took their names off the ballot to satisfy Iowa and New Hampshire, which were unhappy Michigan was challenging their leadoff status on the primary calendar.

"You have a situation now in Michigan where we have what can best be described as a rump primary," Erland said. "This January 15th thing is a fiasco."

He added that he has not coordinated the lawsuit with the Edwards campaign but hopes Richardson and Obama supporters also will back the suit. Erland declined to say whom Hayes supports in the primary, although the suit says the Kent County resident's choice is not on the ballot.

A request for comment was left Tuesday afternoon with the Edwards campaign.

The lawsuit doesn't mention the Jan. 15 Republican presidential primary. Asked if the GOP primary could take place without the Democratic one, secretary of state spokeswoman Kelly Chesney said the department had not had seen the lawsuit, so it would be premature to comment on it.

Gov. Jennifer Granholm and many other Democratic leaders supported the early primary because they said it would make Michigan more relevant in the presidential selection process.

However, the Democratic candidates won't campaign here to avoid angering voters in Iowa and New Hampshire, and national party rules could strip the state of its national convention delegates if Democrats stick with the primary rather than a caucus held Feb. 5 or later.

The Michigan Supreme Court ruled last month in an earlier suit that the law setting up the presidential primary was legal. But that suit focused on who should have access to information on whether each voter chose a Republican or Democratic ballot on Jan. 15. Under current law, only the state GOP and Democratic parties are being given that information.