Former President George W. Bush is wading into Texas’ heated Senate runoff, donating thousands to Sen. John Cornyn’s campaign as the Republican incumbent faces a fierce primary runoff challenge from Attorney General Ken Paxton.

Newly released campaign filings show Bush gave $5,000 to Cornyn’s reelection effort, with $3,500 earmarked for the primary contest and $1,500 for the general election. Under federal law, individual donors may contribute up to $3,500 per election to a candidate committee.

Paxton’s campaign had not yet filed its first-quarter fundraising report as of publication on Wednesday. The Federal Election Commission deadline for candidates to report fundraising totals from January through March is 11:59 p.m. Wednesday.

The race between Cornyn and Paxton remains tight after neither candidate secured a majority in the March primary, forcing a GOP runoff. Polling averages compiled by Decision Desk HQ indicate a narrow margin, with Paxton at 45% and Cornyn at 43%.

Cornyn’s campaign reported raising $1.7 million in the first quarter and finishing the period with nearly $5 million in cash on hand. Including allied political committees, the longtime senator brought in nearly $9 million overall and entered the runoff stretch with more than $8 million available to spend.

“Our campaign works every day to execute our strategy to win the runoff on May 26. A disastrous nominee like Ken Paxton risks our strong Texas House majority and numerous congressional seats,” Cornyn campaign manager Andy Hemming said in a statement to The Hill.

“Sen. Cornyn is our strongest nominee, he is one of President [Donald] Trump’s most effective legislative partners, and our voters will fully understand the choice in this runoff election over the next seven weeks,” Hemming added.

Meanwhile, Democrat nominee James Talarico’s campaign announced it raised more than $27 million during the first quarter.