Washington (CNN) While Congress is on recess, two gun control groups are mobilizing to increase the pressure on senators to pass legislation in the wake of two mass shootings in Dayton, Ohio, and El Paso, Texas, earlier this month.

Everytown for Gun Safety and Moms Demand Action announced Thursday that they would hold rallies in all 50 states and spend nearly $1 million on ads against a handful of Republican lawmakers this weekend.

"The American people want action on gun violence, and we're saying so in a voice loud enough for every senator to hear," John Feinblatt, the president of Everytown, said in a news release Thursday. "We're unleashing the full power of our grassroots movement and leading our most aggressive August spending effort ever, to ensure the Senate gets the message and passes background checks and a strong federal 'Red Flag' law."

Moms Demand Action founder Shannon Watts said she expects more than 100 rallies on Saturday and Sunday in all 50 states. The pressure campaign is in direct response to the recent shootings in Dayton and El Paso, and another in late July at a popular garlic festival in Gilory, California , according to Watts.

"Having the August recess to hold these rallies and also to hold in district face-to-face meetings with senators and their staff is incredibly valuable and important and we're going to going to take advantage of it," Watts told CNN Thursday.

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