While races in other states get the lion’s share of attention heading into the fall campaign season, Democrats — with the help of both conservative and liberal donors — are quietly banking on turning the Wisconsin Senate race, previously deemed a shoe-in for incumbent Republican Ron Johnson, competitive.

In the past week, what was once a crowded Democratic primary field has narrowed to one as every major competitor to Mandela Barnes dropped out of the race and endorsed the lieutenant governor.

Outagamie County Executive Tom Nelson, Milwaukee Bucks executive Alex Lasry, and Wisconsin State Treasurer Sarah Godlewski, once competitors of Mr. Barnes, have become supporters.

Mr. Nelson was the first to drop out on July 25, saying “We ran out of money.” Mr. Lasry dropped out only two days later, even after his family poured more than $12 million of their own billion-dollar fortune into the race. Ms. Godlewski ended her candidacy two days later.

An associate editor at Sabato’s Crystal Ball, John Coleman, argues that the quick consolidation around Mr. Barnes looks like a concerted effort by Democrats to try to avoid a messy primary.

They aren’t the only ones looking to kick Mr. Johnson out of office. Left-leaning organizations such Progressive Turnout Project and Act Blue have joined forces with the conservative Lead the Way Super PAC to fund Mr. Barnes’s campaign. 

In late July, a liberal super PAC, the Family Friendly Action PAC, announced a $23 million effort to turn out suburban women in Wisconsin. Even philanthropist George Soros’ daughter, Andrea Soros has donated a few thousand dollars to Mr. Barnes’ campaign.

The odds of Mr. Barnes winning are subject to debate. Decision Desk HQ gives Mr. Johnson a solid 95 percent chance of winning. The Cook Political Report, on the other hand, rates the race as a toss-up.

At the moment the two are virtually tied in the polls. The latest polling from Marquette Law School suggests that Mr. Barnes has a slight edge, leading Mr. Johnson by two points.

Mr. Coleman, however, argues that those polls should be taken with a grain of salt, cautioning that “Johnson is someone who always gets underestimated.” Polls in 2016 suggested that Mr. Johnson would lose that race, but he didn’t.

“Wisconsin is a very 50-50 state but in a  year like 2022, in the Senate races, it’s going to be driven by whatever Biden’s approval rating is,” Mr. Coleman tells the Sun. “Johnson can more or less just complain and run against an unpopular Biden.”