Candidates backed by U.S. President Donald Trump defeated at least five of the seven Indiana Republican state senators who broke with the party last year by opposing a controversial redistricting measure, according to projections from the Associated Press.

The races marked a significant political victory for Trump and allied political groups, which poured millions of dollars into the normally low-profile primary contests.

The targeted incumbents were among 21 Republican lawmakers who joined Democrats in voting against a mid-cycle redistricting proposal that would have reshaped Indiana’s congressional map in favor of Republicans. Trump had warned ahead of the vote that lawmakers who opposed the plan could face primary challenges.

One incumbent, state Sen. Greg Goode, successfully defended his seat against a Trump-endorsed opponent. Another lawmaker, state Sen. Spencer Deery, remained locked in a close contest late Tuesday against Trump-backed challenger Paula Copenhaver.

A separate Trump-endorsed candidate also appeared headed for victory in a district where an anti-redistricting Republican senator chose not to seek reelection.

Trump celebrated the results on social media, posting images alongside the projected winners as the results came in.

Political observers noted that while Trump’s endorsement carried weight, the races were also shaped by unusually large amounts of outside spending, which overwhelmed incumbents who lacked comparable financial backing.