The Montana Supreme Court's decision on the Green Party candidate could pose a threat to Jon Tester, according to polling data.

Recent polling suggests that a new Montana ruling on a third party's ballot presence could negatively impact Sen. Jon Tester's re-election efforts as he tries to maintain the Democrat's Senate majority.

In an attempt to prevent Green Party Senate candidate Robert Barb from appearing on the November ballot, the Montana Democratic Party filed a lawsuit against Secretary of State Christi Jacobsen and the state of Montana in August.

The Green Party's third-party candidate was named their nominee to replace their original leading candidate who dropped out of the race in August, prompting Democrats to claim in their lawsuit that Barb's nomination was not valid.

In early September, a district court approved the Green Party candidate's ballot access, but the Montana Democratic Party filed a writ of supervisory control to the state's Supreme Court challenging the lower court's ruling. On Tuesday, the Montana Supreme Court upheld the lower court's decision, securing Barb's place on the 2024 ballot.

Although MDP has not convinced us that the District Court erred in its September 3, 2024 Order, we have reached the same result under a different analysis. Since we have not determined that the District Court is acting under a mistake of law, this matter is not eligible for supervisory control.

"I am delighted that the Supreme Court unanimously rejected the Hail Mary attempt to weaken Montana's election law," Jacobsen stated in a Planet Chronicle Digital statement following the decision. "This lawsuit was a politically motivated stunt from Washington elites that disrespected Montana and our election officials from the outset."

The DNC tried to remove Green Party candidate Jill Stein from the presidential debate, despite her receiving more votes than Trump in the state in 2016.

A third party on the November ballot could harm Tester's chances of re-election, according to recent polling.

In a head-to-head matchup against Tester, Sheehy led by six percentage points, according to a recent AARP survey. However, Sheehy's advantage against Tester grew to eight points when other candidates, including the state's Green Party and Libertarian candidates, were included in the race.

Top political handicappers have given Sheehy an edge in the crucial red state race that will determine which party controls the chamber next year.

The Cook Political Report and Sabato's Crystal Ball have both shifted their predictions for the race, with the Cook Political Report moving it from "toss-up" to "lean Republican" and Sabato's Crystal Ball changing it to "leans Republican."