Originally Published: 08 JUL 21 14:43 ET

Updated: 08 JUL 21 15:54 ET

By Dan Merica, CNN

(CNN) -- A series of Democratic Senate candidates announced substantial fundraising hauls this week, putting each campaign in strong financial positions ahead of races that will be critical to the Biden administration's goals.

Arizona Sen. Mark Kelly posted the most significant numbers to date, announcing his campaign had raised nearly $6 million in the second quarter of 2021, ending the three-month period with more than $7 million cash on hand.

"The swell in grassroots support we're seeing is a direct result of Mark delivering in the Senate and will be what fuels our people-powered campaign as we move full speed ahead into 2022," said Emma Brown, Kelly's campaign manager.

While the Arizona Democrat turned in the most substantial number, other Democrats posted big figures.

Rep. Val Demings, who is looking to challenge Republican Sen. Marco Rubio in Florida, announced her campaign raised more than $4.6 million since announcing her bid in early June, ending the quarter with more than $3 million in the bank.

Demings said the "strong support we have generated in such a short period of time shows we will have the grassroots momentum we need to win in 2022."

Rep. Tim Ryan, the Democrat running for Ohio's open Senate seat, announced on Tuesday that his campaign raised $2.28 million in the second quarter and ended the period with $2.6 million in the bank. And John Fetterman, Pennsylvania's Democratic lieutenant governor who is running to fill the state's open Senate seat, announced Tuesday that his campaign raised more than $2.5 million in the second quarter, bringing his total raised since launching the campaign in February to $6.5 million.

"Our campaign has the momentum, staying power, and unmatched grassroots enthusiasm that it will take to not only flip this U.S. Senate seat, but help Democrats across Pennsylvania win up and down the ballot," said Rebecca Katz, a top Fetterman adviser.

The race for the Senate, because the legislative body is currently evenly divided 50-50, will be a top priority for both parties in 2022 given any seat could shift control.

A number of Democratic candidates have yet to announce their fundraising hauls, including three key incumbent senators up for reelection in potentially competitive races: Georgia's Raphael Warnock, Nevada's Catherine Cortez Masto and New Hampshire's Maggie Hassan.

The strong fundraising from Democrats continues a trend that played out during the 2018 and 2020 elections, where Democratic candidates -- partly spurred by the base's opposition to former President Donald Trump -- raised significant money all cycle.

In many cases, however, the money did not lead to victory, with Democratic challengers in places like Iowa, North Carolina, Texas, South Carolina and Kentucky raising large sums of money only to lose on Election Day.

Chris Hartline, spokesman for the National Republican Senatorial Committee, responded to Democrats' fundraising numbers, saying, "Democrats like Mark Kelly and Val Demings are embracing a radical agenda that's hurting American families and is wildly out of touch with what the majority of voters believe. They will lose because of it."

Some Republicans have also announced sizable fundraising hauls for the second quarter of this year.

Josh Mandel, an Ohio Republican vying to win his party's nomination in the state's open Senate election, raised $1.5 million for the quarter, while Jane Timken, another Republican in the race, raised $1.4 million over the last three months.

And Katie Boyd Britt, a Republican candidate for Senate in Alabama running against Rep. Mo Brooks, announced she raised $2.24 million in the second quarter. Britt is a former aide to Sen. Richard Shelby, who is retiring.