An embattled Democrat whose loss could flip the chamber’s party control, a House member looking to replace an indicted incumbent and a challenger with a familiar family name highlight Senate primaries set for Tuesday in Montana, New Jersey and New Mexico.

Democrats now control the Senate by a narrow 51-49 margin. But the decision by West Virginia Sen. Joe Manchin III not to run for another term — he announced Friday he would switch his registration from Democrat to independent but still caucus with the majority — makes it likely that state will go to the GOP in November.

As a result, flipping one more seat would give the Republicans a majority. They could also control the chamber if it is split 50-50 and Donald Trump is returned to the White House since the vice president would break ties.

Here’s a rundown of the races with primaries on Tuesday.

Kim looks to move up in New Jersey

Rep. Andy Kim is the favorite to win the Democratic nomination in New Jersey’s Senate race, but he’ll have to defeat Patricia Campos-Medina, a labor leader, and perennial candidate Lawrence Hamm first.

A three-term House member with a background in foreign policy, Kim announced his Senate campaign the day after incumbent Democratic Sen. Bob Menendez was indicted in September and refused calls to resign. Kim earned the support of progressive and grassroots groups and won several county conventions against Tammy Murphy, the wife of Democratic Gov. Phil Murphy, before she ended her campaign in March.

Kim also seemingly upended the state’s style of machine politics after bringing a lawsuit to challenge the state’s ballot design that gave preferential placement to candidates who had secured “the line,” a bracket that had the county organization’s backing. A federal judge granted a preliminary injunction in March, and Democratic ballots for Tuesday’s primary don’t feature the format. 

Two outside groups, End Citizens United and Indivisible Action, spent a combined $29,000 to support Kim’s campaign ahead of the primary.

Four candidates are running in the Republican primary. Curtis Bashaw, a hotelier, and Christine Serrano Glassner, the mayor of Mendham, are the leading candidates. Navy veteran Albert Harshaw and former Tabernacle Deputy mayor Justin Murphy are also running. 

A group called Jersey Deserves Better PAC spent $19,000 to support Serrano Glassner’s campaign and $19,000 to oppose Bashaw’s. 

Kim is well positioned for the fall campaign, with $4.1 million in his campaign account on May 15. Bashaw had $525,000 and Serrano Glassner $262,000.

In addition to it being primary day, Tuesday is also the last day for Menendez — who is currently on trial for 16 criminal counts, including bribery, extortion and acting as a foreign agent — to file to run as an independent candidate. Menendez had said he would run as an “independent Democrat” if exonerated, as he expects to be. He reportedly has gathered the minimum 800 signatures needed to run. 

Tester, Sheehy ready for Montana face-off

A big battle is looming in Big Sky Country with Sen. Jon Tester, one of the chamber’s most vulnerable incumbents, set to face Republican challenger Tim Sheehy in November.

Both candidates have nominal primary opponents: Navy veteran Michael Hummert is running against Tester, while former Montana Secretary of State Brad Johnson and environmental contractor Charles Walking Child are on the Republican ballot. But Tester and Sheehy are all but certain to be their party’s respective nominees.

Tester enters the general election campaign with one of the largest war chests of any Democratic incumbent. He had about $11.8 million on hand as of May 15, far outpacing Sheehy’s $2.2 million.

But Sheehy is a top GOP recruit, and Republicans are hopeful the businessman and former Navy SEAL can use his personal wealth to unseat the Democratic incumbent, who was first elected in 2006. Montana has become increasingly friendly territory for the GOP, with then-President Donald Trump winning the state by more than 16 points in 2020. The race is rated Toss-up by Inside Elections with Nathan L. Gonzales.

Outside groups are expected to play an outsize role in a race that will help determine which party controls the Senate. More Jobs, Less Government — a super PAC aligned with Sen. Steve Daines, the state’s junior senator who is head of the National Republican Senatorial Committee — has spent $1.6 million opposing Tester and $5.1 million in support of Sheehy. Meanwhile, the Last Best Place PAC, a super PAC affiliated with Democrats, spent $4.5 million opposing Sheehy.

Domenici name on New Mexico ballot again

In 2018, Sen. Martin Heinrich handily won a three-way race against Republican Mick Rich and former Gov. Gary Johnson, who ran on the Libertarian ticket.

This year, the GOP thinks Nella Domenici might be able to unseat the two-term Democrat. Domenici is the daughter of Pete Domenici, the last Republican to represent New Mexico in the Senate. She is the former chief financial officer of Bridgewater Associates, the world’s largest hedge fund.

Neither Heinrich nor Domenici is facing a primary. Heinrich had $4.4 million in his campaign account as of May 15 to Domenici’s $1 million. The race is rated Solid Democratic; President Joe Biden won the state by nearly 11 points in 2020. 

But Republicans believe Domenici’s family name and Bridgewater connections could give her a significant boost in a race that has the potential to become competitive, or at least to require Democrats to spend money defending Heinrich.