Montana's vulnerable Sen. Jon Tester will not be making an endorsement in the presidential election where Vice President Kamala Harris is running as the Democratic nominee, despite reportedly playing a role in her recruitment to the Senate.

Tester previously served as chair of the Democratic Senatorial Campaign Committee (DSCC) from 2015 to 2017, leading the efforts of the campaign arm to elect Democrats to the chamber when Harris first announced her senatorial aspirations.

After Harris launched her California Senate bid, the Los Angeles Times reported in January 2015 that, according to an adviser, Tester was one of the players encouraging her to run.

Despite his previous support for Harris, Tester said he will not be making an endorsement in this year's race because he will be focusing on his own re-election bid. 

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Sen. Jon Tester arrives for the Senate Appropriations Subcommittee on Defense hearing on Capitol Hill, June 18, 2024.

Sen. Jon Tester arrives for the Senate Appropriations Subcommittee on Defense hearing on Capitol Hill, June 18, 2024. (Tom Williams/Getty Images)

"I’m not going to endorse for the presidential – and I will tell you why," Tester said during a recent press conference in Hamilton, Montana. "Two reasons: No. 1, I’m focused on my race. And No. 2, folks have wanted to nationalize this race, and this isn’t about national politics. This is about Montana."

Tester, however, endorsed Harris for vice president after she was tapped as President Biden's running mate in 2020.

"My friend @KamalaHarris is a proven fighter and an excellent pick for Vice President. As VP, I'm confident she will continue to fight for working families across this country. Looking forward to supporting her and @JoeBiden in November," Tester wrote in an August 2020 post on X, formerly known as Twitter.

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Kamala Harris at a bilateral meeting with Israeli Prime Minister Benjamin Netanyahu

Vice President Kamala Harris (Kenny Holston/Getty Images)

The senator has remained distant from the Democratic ticket for several months, as he seeks re-election in a state former President Trump won by 16 points in 2020.

"No matter who is in the White House, Jon Tester always does what’s right for Montana. It’s why Jon has consistently stood up to the Biden-Harris administration on issues like securing the border and protecting Montana from burdensome energy regulations, and it’s why President Trump signed more than 20 of his bills into law," Monica Robinson, spokesperson for Montanans for Tester, told Fox News Digital. "Jon’s strong record of defending Montana is why Republicans from across the state, from elected officials to business owners to Trump voters, endorsed Jon in his campaign for Senate."

The Montana Democrat was one of the first senators to call on Biden to drop out of the 2024 race in July.

Tester was also one of three vulnerable Senate Democrats who did not attend the Democratic National Convention (DNC), where Harris officially accepted the party's nomination for president. 

Tim Sheehy

Montana Senate candidate Tim Sheehy speaks during the Republican National Convention in Milwaukee, Wisconsin, July 16, 2024. (Andrew Caballero-Reynolds/Getty Images)

Tester faces opposition in one of the most crucial Senate races of the 2024 cycle from former Navy SEAL Tim Sheehy, who said, "Jon Tester skipping Kamala Harris’ DNC coronation will not hide the fact that he launched her political career by recruiting her to the U.S. Senate and votes with her radical agenda 95% of the time."

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"Jon Tester, Kamala Harris and Tim Walz are all loyal America Last Democrats who support open borders, amnesty and checks for illegal immigrants, higher taxes, and Green New Scam energy policies that Montanans will reject in November," Sheehy said in a statement shared with Fox News Digital. "Come November, Montanans will help send President Trump back to the White House and put an end to the insanity of the disastrous Harris-Tester agenda for good." 

The Cook Political Report, a top nonpartisan political handicapper, currently positions Tester's race as a "toss-up."