By Eliza Collins | Photographs by Janie Osborne for The Wall Street Journal

BUTTE, Mont. -- Democratic Sen. Jon Tester has weighed the needs of his rural electorate with the demands of his party's leadership ever since he joined the Senate, winning three times in the solidly conservative state.

Now, a series of votes on infrastructure, election rules and other contentious issues expected this summer will challenge his balancing act and help determine the course of President Biden's multitrillion-dollar spending and tax plans.

The Senate is divided 50-50, meaning Democrats can't afford to lose a single vote absent GOP support. Other Democrats including Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona have used their leverage to publicly pull bills to the center and demand bipartisanship. For the most part, Mr. Tester hasn't to date: He has been a reliable supporter of Democrats' agenda, breaking only occasionally with leaders on issues such as energy and taxes.

"Everybody's got their different style," Mr. Tester, 64 years old, said as he ate a roast beef and turkey sandwich in his Butte office last week. "My style is: I want to get s -- done, OK? And I think, you know, being on TV and then having a gang of reporters around you is just fine, but it doesn't help me get things done."

But as with other Democrats, he is facing friction from the party's agenda as he returns from a recess spent in his home state. There, his family is farming wheat, peas, barley and hay on the same land his grandparents homesteaded in 1912 near Big Sandy, current population less than 600.

In Washington, Mr. Tester has split with many Democratic lawmakers and activists by declining to back efforts to end the filibuster, the rule requiring that most Senate bills get 60 votes to advance. But unlike Mr. Manchin and Ms. Sinema, who have opposed the change, Mr. Tester has indicated flexibility on the matter.

Asked if the recent GOP filibuster blocking a bipartisan commission to look at the Jan. 6 Capitol riot would influence his stance, he responded, "I don't think we're there yet but it certainly has its effect." He added: "It depends what the future holds and my crystal ball is not that clear."

Mr. Tester has joined other centrists in saying he wants any infrastructure package to have bipartisan support, but he has signaled he would support a Democrat-only approach if negotiations fail. The White House has continued to hold talks with Republicans, but the two sides remain far apart on the size of the package and how to pay for it.

"Overall, I think, bipartisan legislation has a better chance of standing the test of time. But that being said, I didn't come to sit on my hands," he said.

Mr. Tester has raised objections to Mr. Biden's proposal to impose capital-gains taxes on unrealized asset appreciation upon a person's death, with the new revenue used to fund Mr. Biden's antipoverty or infrastructure plans. The tax has a $1 million per-person exemption, plus the existing exemption for principal residences and special rules that would let farms and other businesses defer payments as long as they are family-owned and operated. Mr. Tester, like other rural Democrats, said the proposal would hurt farmers and called it a nonstarter.

"I'm a small farmer in eastern Montana, and it would have significant effects on me," he said.

Some Democrats say the need to remove the filibuster will come to a head this summer when the Senate votes on legislation setting new rules on how elections are conducted. Mr. Tester stood up during a private Democrats' lunch last month and made a plea for them to pass the legislation, though he hasn't said he would support nixing the filibuster over it. All Democrats except Mr. Manchin support the bill; no Republicans are expected to back it.

Activists who want to see the filibuster abolished say they think Mr. Tester will be there when they need him.

"He is a great example of a senator who supports the filibuster but sees its abuse and sees it's no longer working and is now open to change," said Eli Zupnick, a spokesman for Fix Our Senate, a coalition of dozens of organizations that want to abolish the threshold.

Mr. Tester's supporters point to what they see as his authenticity as the reason he keeps winning, even if voters don't agree with everything he does. His opponents acknowledge his appeal as a regular guy, but they say his record is out of step with an increasingly Republican electorate in the state, where former President Donald Trump won by 16 points in 2020.

Mr. Tester and his wife, Sharla Tester, run their organic farm themselves, and he sometimes puts in 12-hour days during planting and harvesting season. He is missing three fingers from an accident in a meat grinder when he was 9. He still uses the same grinder and brings beef he butchers himself in a cooler when he travels to D.C.

"He's salt of the earth; he is Montana," said Sandi Luckey, the executive director of the state Democratic Party.

Republican State Sen. Bob Keenan, who was the minority leader when Mr. Tester was Montana Senate president and vice versa, said the Democrat should be associated with the party's more liberal members because that is how he votes.

"He's no Joe Manchin; you don't hear Jon bucking the party," Mr. Keenan said.

Mr. Tester did publicly break with Mr. Biden's decision to revoke the permit for the Keystone XL pipeline. Local activists say he isn't doing enough to address climate change.

"Sen. Tester is someone who we need to constantly worry about, in terms of will he vote the right way?" said Lucy Hochschartner, 23, a volunteer with a local branch of the progressive climate group Sunrise Movement.

Montana's Republican Sen. Steve Daines said he and Mr. Tester have worked together on a number of issues including conservation and tribal water rights. But they disagreed on others that he said are important to the state, such as Mr. Trump's three nominees to the Supreme Court, all of whom Mr. Tester opposed, and the GOP's 2017 tax overhaul, which Mr. Tester voted against.

Mr. Trump targeted Mr. Tester in 2018, visiting the state four times, after he released information that ultimately sank the nominee to lead the Department of Veterans Affairs. But Mr. Tester survived, helped by support from veterans and union members. Mr. Tester, now chairman of the Veterans Affairs committee, has given priority to the issue. Sen. Jerry Moran (R., Kan.), the top Republican on the committee, said they have worked well together, including efforts to pass a law for mental-health care for veterans. Local activists praise Mr. Tester's work getting funding for the Southwest Montana Veterans Home, set to be finished this summer.

Mr. Tester's work with veterans "has been probably more of the secret sauce than anything," said one Montana Republican aide.

In his first campaign for the Senate, Mr. Tester accused his incumbent GOP opponent of spending money "like a drunken sailor." These days, Mr. Tester says both sides spend a lot of money, just on different things. "Where do you want to spend it? You want to spend it on giving tax breaks to rich people? Do you want to spend it on infrastructure?"

Mr. Tester said he doesn't worry about political expediency since voters already know where he stands. He said he backed Mr. Biden's $1.9 trillion coronavirus relief package earlier this year -- despite wishing the $1,400 checks went to a more targeted group of people -- because he wanted to quickly get funding to small businesses and local governments. On Mr. Biden's infrastructure proposal, Mr. Tester said the spending will be necessary to be able to compete with China.

His approach has worked so far. At a recent Memorial Day event in Butte where Mr. Tester spoke and played "Taps" on his trumpet, he had supporters in the audience who also backed Mr. Trump.

"I think he's awesome. I think he does a great job," said Diane Sholey at the event. Ms. Sholey, an 82-year-old retiree, voted for Mr. Tester in 2018 and Mr. Trump in 2020. She said even though she was a Republican, she didn't mind Mr. Tester's voting record.

But Donald Johnson, 77, an author and veteran from Helena, said he wants to see Mr. Tester out of office.

"I don't like the way the Democrat Party has recently leaned very extreme," he said.

--Siobhan Hughes and Richard Rubin contributed to this article.

Write to Eliza Collins at eliza.collins+1@wsj.com.

(END) Dow Jones Newswires

06-07-21 0826ET