JEFFERSON CITY, Mo. — Democratic U.S. Sen. Claire McCaskill of Missouri says she has more than $5 million to spend on her 2018 re-election campaign.

McCaskill’s campaign in a Monday statement announced she raised more than $3 million between April and June.

She’s building a war chest in face of an upcoming fight over her Senate seat. She’s among 10 Senate Democrats running in 2018 in states won by President Donald Trump.

So far there’s no front-runner Republican candidate to face off against McCaskill. GOP U.S. Rep. Ann Wagner has said she’s instead running for re-election.

Former Libertarian presidential candidate Austin Petersen and Tony Monetti, executive director of Central Missouri’s airport, are running as Republicans.

Several high-profile Republicans have also encouraged Missouri Attorney General Josh Hawley to run.