Sen. Jon Tester (D-Mont.) is emerging for a make-or-break player for President Biden’s agenda in the Senate.  

Tester could be the deciding vote on some of Biden’s controversial nominees, such as Eric Garcetti, the president’s embattled pick to serve to serve as ambassador to India, and Phillip Washington, Biden’s choice to head the Federal Aviation Administration.  

Biden’s announcement last week that he will sign a GOP-sponsored resolution to block a controversial new D.C. crime bill gives Tester political cover to vote for it this week.  

Tester may vote for another Republican-sponsored resolution that would block a rule from Biden’s Environmental Protection Agency and U.S. Army Corps of Engineers that expands federal jurisdiction over streams and wetlands.

And he voted last week for a GOP-sponsored resolution to block a Biden Labor Department rule encouraging retirement managers to consider environmental, social and governance factors when making investment decision. 

“He’s not only a crucial swing vote but he’s No. 25 in seniority in the Senate now and he’s got two key chairmanships. He’s chairing the defense subcommittee on appropriations and he’s chairing [the] Veterans Affairs [Committee.] So those give him a bully pulpit and a chance to do some things,” said David McCumber, a resident of Butte, Mont., who serves as the local news director in the Western United States for Lee Enterprises.  

Tester, who serves as chairman of the Defense Appropriations Subcommittee, is leading a Senate investigation into the Biden administration’s handling of a Chinese spy balloon that floated across Montana and other parts of the country last month.  

McCumber noted that “Montana by all appearances has turned hard right” but he thinks Tester “remains in a pretty good position” to win re-election.  

“I think he’s going to be even more visible than he’s been in the past these next two years,” he said.  

Christopher Muste, a professor of political science at the University of Montana, said Tester has always had an independent streak but has tended to be “quieter” about it compared to higher-profile centrists such as Sens. Joe Manchin (D-W.Va.) and Kyrsten Sinema (I-Ariz.). 

Tester, for example, tried to amend COVID relief legislation in March of 2021 with a proposal to allow construction of the Keystone XL pipeline to move forward without a presidential permit.

And he voted for a GOP-sponsored resolution in December of 2021 to nullify Biden’s COVID vaccine mandate for private businesses.  

“He’s been someone who’s used his leverage in the past to try to get more attention to issues that are relevant to Montanans,” Muste said. “I expect him to do so fairly quietly on national terms.”

Muste said Tester’s willingness to buck his party’s leadership will help thwart efforts by Republicans in Montana to nationalize the Senate race by tying him to Biden and Senate Majority Leader Chuck Schumer (D-N.Y.).  

Tester’s vote is becoming more critical to the Biden agenda as fellow endangered Senate Democrat Manchin increasingly aligns himself with Republican colleagues.  

Manchin has partnered with conservative Sen. Ted Cruz (R-Texas) on legislation to stop the federal government from banning gas stoves — something that most Democrats dismiss as a red herring — and criticized Transportation Secretary Pete Buttigieg’s handling of the train derailment in East Palestine.  

Both Tester and Manchin face tough re-election races next year in states that former President Trump won by large margins in 2016 and 2020.  

Tester announced last month that he would run for a fourth Senate term while Manchin has yet to reveal his plans for 2024.  

With Manchin shifting to the right in a 51-49 Senate Democratic majority, Tester is now positioned as the Senate’s most critical swing vote. 

He and Manchin were the only two Senate Democrats to vote to block the Biden rule encouraging retirement managers to weigh environmental, social and corporate governance factors. 

The passage of that resolution has set the stage for Biden’s first veto.   

Sen. Mike Braun (R-Ind.), the lead Republican sponsor of the resolution on environmental, social and corporate governance guidance, said voters in Montana don’t “want federal directives on how your money managers can invest your money.”  

Braun said a key different this year compared to Biden’s first two years in office is that Democrats now have a one-seat majority and “it will take more than just Joe” Manchin to block items on Biden’s agenda.  

The media spotlight focused more on Manchin and Sinema in the last Congress as those two senators stood as the biggest obstacles to Biden’s Build Back Better agenda in the 117th Congress. 

But a new political dynamic is emerging in the Senate in 2023 as Sinema, a newly declared independent, has to worry about a Democratic challenger if she runs for a second term.  

Rep. Ruben Gallego (D-Ariz.) has already announced he will run for her seat. 

Tester won’t say how he’s going to vote on Garcetti or the resolution to block the D.C. crime bill, which now is expected to pass the Senate with a large majority of votes after Biden announced Thursday he would sign it into law.  

He also played his cards close to the vest before the vote on the environment, social and governance investing rule.  

“I’ve been so damn busy,” he said, explaining why he hadn’t yet made up his mind on the crime bill and Garcetti.  

On Wednesday, Tester warned Biden to tread cautiously after the president said at an event in Virginia Beach that he could call for tax increases in his budget proposal.  

“If it’s about tax equity we’ll take a look at it. If it’s about across-the-board tax increases for everybody it’s probably the wrong time to do it because of inflation,” Tester told The Hill.  

A spokesman for Tester said his boss will “always take on anyone in Washington to do what’s best for his state.” 

“As a third-generation farmer who still farms the same land his grandparents settled more than 100 years ago, Jon knows firsthand that people in Washington don’t understand what a hard day’s work looks like or the challenges working families are facing in Montana,” the aide said. 

McCumber, the news director based in Butte, said Tester’s going to buck Biden on some high-profile issues.  

“Sure he’s going to do that, he’s going to take every opportunity to play to Montana. At the same time, he’s not going to do anything that he doesn’t believe in. He’s been a lot better Democrat than Manchin’s been,” he said. “He’s also drawn a line in the sand when he’s felt like he needed to. 

“When there’s an omnibus defense bill and there’s something for Montana, he’s going to get it,” he said. “It’s going to be tougher to beat him, I think, this time than it was last time.” 

Tester narrowly defeated then-state auditor Matt Rosendale (R) in the 2018 midterm election. Rosendale, who is now represents Montana’s 2nd Congressional District, is a possible candidate to challenge Tester next year.