State Democrats succeeded in kicking the Green Party off the ballot in Montana this week, with the Montana Supreme Court ruling that they must be dropped.

The decision could impact the tight U.S. Senate race between Republican Sen. Steve Daines and sitting Democratic Gov. Steve Bullock – one of several that could determine control of the U.S. Senate.

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The ruling happened after massive pressure was put on people who had already given valid signatures for a petition for Green Party ballot access, according to Green Party representatives.

“The Green Party denounces any effort to harass, intimidate or shame private citizens who signed a ballot access petition for any party or candidate,” National Green Party communications manager Michael O'Neil said in a statement to Fox News. “Our candidates have faced that kind of political bigotry for decades but employing it against regular citizens on this scale marks a new, shameful low.”

The Democrats succeeded in getting some 500 petition signatories to recant their signatures after alleging the petition was backed by Republicans (the party reportedly helped finance the effort), although no law specifies a process for such removal. The withdrawals left the Green Party short of the signatures needed.

State Green Party officials initially said the party wasn't involved in the petition, but the National Green Party condemned what happened -- and one candidate said the state party is now getting involved to defend the validity of it.

"There was a great deal of pressure applied to [petition signers] to get them to withdraw their signatures. Multiple phone calls with strong language, and repeated letters," local Montana Green Party candidate Gary Marbut, who is running for state Senate but is not competing in the U.S. Senate race, told Fox News. (The U.S. Senate candidate for the party is Wendie Fredrickson.)

Marbut and other Greens will now take their case to federal court, and filed Thursday for an emergency injunction with the 9th Circuit Court of Appeals, arguing kicking Greens off the ballot infringes on voting rights. The Montana Secretary of State is separately appealing directly to the U.S. Supreme Court, arguing that the Greens should be allowed on the ballot.

The parties are fighting over the Green Party's ballot access because the Montana Senate race this November may determine control of the Senate – and politicos think that the Green Party could be a “spoiler” that draws votes away from Democrats.

Third-party proxy wars are not new in Montana. In 2012, supporters of Democrat Jon Tester spent $500,000 supporting the Libertarian Party candidate in hopes that he'd draw votes away from the Republican. It may have worked, as Tester won by 18,000 votes, while the Libertarian candidate received 31,000.

The Democrats, in their campaign to get Green signatures “taken back,” pointed out that this year, Republicans indirectly hired canvassers to collect signatures for Green Party ballot access.

“We are not naive about Republican Party operatives' motivations,” the Green Party’s O'Neil said. “They believe it undermines their counterpart within the two-party cartel. The Green Party rejects the idea of any candidate ‘taking away the vote’ of another candidate. Votes belong to the voters until the moment they are cast. Candidates must earn those votes.”

U.S. Senator Steve Daines, R-MT, walks from the Senate floor between votes on procedural measures leading up to potential tax overhaul legislation at the U.S. Capitol in Washington, U.S., December 1, 2017. 

U.S. Senator Steve Daines, R-MT, walks from the Senate floor between votes on procedural measures leading up to potential tax overhaul legislation at the U.S. Capitol in Washington, U.S., December 1, 2017.  (REUTERS/Jonathan Ernst)

The court ruling to strike the Green Party from the ballot comes after the state of Montana had already certified the Green Party for the ballot earlier this year and conducted a Green Party primary, in which 800 Montanans voted. Marbut says the new ruling violates the federal rights of those voters.

As it stands, the ruling removes the Greens from the general election ballot at all levels, including the presidency. The Senate race is expected to be most consequential nationally.

The state Republican Party told Fox News that Bullock wants to avoid critiques from the Green Party.

“The Montana Democratic Party spent tens of thousands of dollars to suppress Green Party voices ... all so Governor Bullock won't have to face a Green Party candidate that will expose his administration's corruption,” Montana GOP Executive Director Spenser Merwin told Fox News in a statement.

The Montana Democratic Party did not return a request for comment.

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Marbut says he and other Greens are now mounting an effort to get signatories to recant their withdrawals -- to flip back a second time.

One of Marbut’s volunteers, Debbie Rowe, said she talked at length with signatories who were pressured by Democrats to recant.

"The Democratic Party had called most of them about 15 to 25 times to badger them to do a withdrawal," she told Fox News.

"One elderly couple told me that they just didn't feel comfortable saying 'no' after the 20th call they received. The Democratic Party even had a third-party notary come to their house to take their withdrawal; I think that scared some people, too -- they think, 'now they know where we live.'"

Democrats had told petition signers that they should remove their names because the ballot effort was aided by Republicans and was not the work of the true Green Party.

But the national Green Party calls the petition “valid.”

“The Green Party wishes for the valid petition submitted in Montana to stand and for Green Party candidates, including presidential nominee Howie Hawkins ... to appear on the Montana ballot,” O'Neil said. “Candidate suppression is a form of voter suppression and, by that measure, Democratic Party leaders are as guilty as anyone of voter suppression in this century.”

Marbut said he finds the attempt to remove ballot access ironic.

“I'm only mildly surprised at this extreme effort by Democrats to be undemocratic,” Marbut said.

Maxim Lott is Executive Producer of Stossel TV and creator of ElectionBettingOdds.com. He can be reached on Twitter at @MaximLott.