The Montana Democratic Party will make its case in Lewis and Clark County Court on Tuesday against the Montana Green Party appearing on election ballots this year.

Democrats say the Greens didn’t collect the required number of voter signatures on its petition to quality as an official political party on this year’s November ballot.

The Democratic Party names the Green Party, and Montana’s Republican Secretary of State Corey Stapleton, as defendants. The suit was filed soon after the Secretary of State’s office certified in mid-March that the Green Party had submitted enough signatures.

Democratic Party officials declined to be interviewed, and are referring all questions about the challenge to their lawyers.

Green Party state coordinator Danielle Breck says her party is organizing a rally at the courthouse Tuesday. She says some former Democratic Party supporters, like herself, want a new option for a left-leaning platform.

"Well, if the Democratic Party isn’t going to be willing to listen to the voters, our best option is to build a new movement and to build a new party," said Breck.

Democrats are charging that 180 of the signatures turned in by the Green Party are invalid, enough to keep them from appearing on the fall ballot.

If the challenge fails, Green Party candidates could result in fewer progressive leaning voters choosing Democratic Party candidates this year.

The hearing in Lewis and Clark County District Court is scheduled for 1:30 p.m. Tuesday afternoon.