Additional Republicans are tossing their support behind Josh Shapiro, the Democratic nominee for governor of Pennsylvania, as he seeks to defeat Trump-backed GOP nominee Doug Mastriano in the state's November gubernatorial election.

The group of seven Republicans who endorsed Shapiro this week, according to Shapiro's campaign, includes former Bush-era Homeland Security Sec. Michael Chertoff, chair of the Delaware County Council and former Pennsylvania state Rep. Mario Chivera, former Bucks County District Attorney David Heckler, former Pennsylvania state Rep. Raymond Blunt Jr., former Pennsylvania state Rep. Jim Kelly, former state Rep. Beverly Mackereth, and former Pennsylvania state Rep. J. Scot Chadwick.

In a statement shared with Fox News Digital, Shapiro, the current attorney general for the Keystone State, insisted he is "proud to receive the endorsement of these Republican leaders who are putting our Commonwealth ahead of partisan politics in order to come together and move Pennsylvania forward."

"From cutting taxes and getting our economy moving again, to improving our schools and keeping our communities safe, I know we can work together to get things done for Pennsylvania," he said. "I have always worked to bring Republicans and Democrats together – and that’s exactly what I will continue to do in this campaign and as Governor."

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Josh Shapiro

Pennsylvania Democratic gubernatorial nominee Josh Shapiro campaigns in Philadelphia, Pennsylvania, on August 18, 2022. (Dave Kotinsky/Getty Images for SEIU)

Citing Mastriano's embrace of "dangerous extremism," Chertoff, who served at the Department of Homeland Security from 2005 to 2009, said he is "proud" to support Shapiro in the election.

"I dedicated my career in public service to upholding the rule of law and defending the Constitution. Right now, we all have a responsibility to support candidates of whichever party who will stand up and defend our democracy," Chertoff said in a statement.

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"Although I am a long-standing Republican, I am deeply troubled by Doug Mastriano’s embrace of dangerous extremism," Chertoff added. "Josh Shapiro, on the other hand, is a staunch defender of our democratic institutions and will lead Pennsylvania with honor and integrity. I am proud to support his campaign for Governor."

Michael Chertoff

Former DHS Sec. Michael Chertoff, a self-described "long-standing Republican" said he is "proud" to support Shapiro's campaign for governor of Pennsylvania. (Drew Angerer/Getty Images)

The second wave of GOP support for Shapiro, who formerly served as Montgomery County commissioner from 2011 to 2017 and as a representative in the state from 2005 to 2011, comes more than a month after nine Republicans in the state announced their support for his gubernatorial campaign.

The initial group of Republicans who endorsed Shapiro last month includes former House Reps. Charlie Dent and Jim Greenwood, former Pennsylvania Supreme Court Justice Sandra Schultz Newman, former Pennsylvania Speaker of the House Denny O'Brien, former Pennsylvania state Rep. Dave Steil, former Pennsylvania state Rep. Lita Cohen, former Pennsylvania Lt. Gov. Robert Jubelirer, Chairman of the Lawrence County Board of Commissioners Morgan Boyd, and former Montgomery County GOP Chair Ken Davis.

Doug Mastriano

Pennsylvania Republican gubernatorial candidate Doug Mastriano speaks to supporters at the Unite and Win Rally at the Wyndham Hotel on August 19, 2022 in Pittsburgh, Pennsylvania. (Jeff Swensen/Getty Images)

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The newly announced endorsements follow a report from Reuters last week that claimed Mastriano, a retired Army colonel who has received the backing of former President Donald Trump and Florida Gov. Ron DeSantis, posed for an Army War College faculty photo in a Confederate uniform in 2014.

Fox News did not receive an immediate response about the endorsements from the Mastriano campaign.