Republican U.S. Sen. Rand Paul posted his best fundraising haul in the past quarter, surpassing the amounts he raised in any three-month period from his two previous successful Senate campaigns in Kentucky, his campaign said Tuesday.

Paul, who is seeking another term next year, raised more than $4 million in the period between July 1 and Sept. 30. The quarter began with Democrat Charles Booker launching his bid to unseat Paul, potentially setting up a battle between candidates with starkly different philosophies. Paul is a libertarian-leaning conservative while Booker touts an activist role for the federal government.

Booker, a former state lawmaker, said in a social-media post Tuesday that he has raised $1.7 million from more than 55,000 contributions across Kentucky since entering the campaign.

Paul’s deputy campaign manager, Jake Cox, said the senator’s record-setting fundraising quarter is “a strong sign that Kentuckians want to see Dr. Paul return to the Senate in 2022.”

Paul, a former presidential candidate, has raised more than $9 million this year for his reelection bid and had nearly $7 million in the bank at the end of the just-ended quarter, his campaign said.

He has received contributions from more than 150,000 “small-dollar, grassroots donors” this year, his campaign said.