A newly formed super PAC with a name resembling a progressive climate group has entered a competitive Democratic primary in Michigan, drawing attention from Democrats and political observers.

The Down Ballot reported Monday that “Michigan Sunrise PAC,” a group that emerged only days ago, has already spent nearly $600,000 to boost progressive candidate William Lawrence in the crowded race to challenge incumbent Republican Rep. Tom Barrett this fall for Michigan’s 7th Congressional District.

Super PACs may raise and spend unlimited sums on independent expenditures, but they are legally barred from coordinating those expenditures with candidates. That structure can make outside spending especially consequential in crowded primaries, where a relatively late advertising push can change what voters hear about multiple candidates before Election Day.

Operatives in both parties suspect Republicans may prefer Lawrence as the Democratic nominee in the swing district, according to the report. Lawrence, a co-founder of the Sunrise Movement, a climate advocacy organization, has been viewed by some Democrats as the weakest general-election candidate in the field.

The PAC’s advertisements criticize rival Matt Maasdam over old Florida voter registration records while promoting Lawrence’s profile, including a reference to support from Bernie Sanders. Maasdam is a former Navy SEAL. The ads do not mention Bridget Brink, the third contender in the race.

“The more moderate Brink and Maasdam have spent a good deal of time attacking one another on the airwaves, potentially leaving an opening for Lawrence to win the nomination,” The Down Ballot reported. “It’s that opening that Republicans may now be looking to exploit.”

The new group uses a small South Dakota financial institution that has also been used by Republican officials, a detail that has drawn scrutiny from political watchdogs.

“The name of the PAC, of course, is very similar to that of the organization Lawrence helped create, but the two appear unconnected,” The Down Ballot reported. “Rather, the Sunrise Movement has its own PAC, called Sunrise PAC. While the Sunrise Movement has endorsed Lawrence, its PAC has not reported spending any money on this race.”

The top House GOP super PAC did not respond when Axios reporter Andrew Solender asked for comment.

If confirmed, the activity would mark the 18th instance this election cycle in which Republicans have allegedly intervened in a Democratic primary, The Down Ballot reported. The scrutiny now centers on whether further campaign finance filings or ad disclosures clarify who is funding Michigan Sunrise PAC and how much more it plans to spend in the race.