WASHINGTON — Sen. Bob Casey (D., Pa.) finished March with more than $10 million in his reelection fund, setting a new high for a Senate candidate from Pennsylvania, his campaign said.

The cash-on-hand total reflects one measure of political strength, and shows rivals how much Casey has to spend for the final seven months of campaigning. It's the most any Pennsylvania Senate candidate has had in the bank at the end of a quarterly reporting period, Casey's campaign said, citing past public disclosures in sharing the figure with the Inquirer and Daily News.

National Republicans have targeted Casey, hoping that after President Trump won Pennsylvania in 2016 they can oust the Democratic incumbent.

The cash-on-hand sum is not a measure of pure fundraising power, since it also factors in how much a candidate has spent or saved. Sen. Pat Toomey (R., Pa.), for example, had collected more money overall — $19 million — at a similar point in his 2016 reelection campaign. Casey has raised around $15 million this election cycle, including $2.2 million in the first three months of 2018.

Casey's total serves as a reminder of the fund-raising gap between the incumbent and his leading Republican rival, U.S. Rep. Lou Barletta.

Barletta had about $1.1 million on hand as of Dec. 31, the date of his latest filing. His campaign has not yet released its fundraising totals for the first quarter of 2018.

Casey's sum reflects his fund-raising and campaign spending through the end of March, the cutoff for public disclosures due later this month. His campaign manager, M.E. Smith, attributed the sum to "overwhelming grassroots enthusiasm."

Another Republican candidate, State Rep. Jim Christiana, had roughly $18,000 in his campaign fund at the end of last year.