PHILADELPHIA — The ranks of Republicans rejecting State Sen. Doug Mastriano, their party’s nominee for governor in Pennsylvania, grew this week as a former national security Cabinet member and a former Trump administration lawyer endorsed the Democratic nominee, state Attorney General Josh Shapiro.

Michael Chertoff, who served as secretary for the U.S. Department of Homeland Security from 2005 to 2009 under then-President George W. Bush, said he considers Mastriano “a real threat to the values of the rule of law” because Mastriano has pushed lies about the 2020 presidential election and was present at the U.S. Capitol as the Jan. 6, 2021, riot unfolded.

Chertoff, a former federal judge and former assistant attorney general, said he has been following the news about Mastriano’s positions.

“I know what he’s articulated,” he said. “It’s not much of a mystery. He’s not hiding his views. He’s in fact courting people who think we should revisit the 2020 election.”

Former President Donald Trump, who endorsed Mastriano just before May’s primary, used his social media platform Truth Social on Monday to declare the 2020 election should be overturned and redone. Trump will appear Saturday at a rally in Wilkes-Barre for Mastriano and “the entire Pennsylvania Trump Ticket.”

James Schultz, a former associate White House counsel for Trump, on Monday published an essay in Philadelphia Magazine that also rejected Mastriano due to his 2020 election claims and Jan. 6 participation.

He noted that party organizations such as the Republican Governors Association have not come out in support of Mastriano.

“The rhetoric and the record coming out of Mastriano’s campaign doesn’t represent the values of Republicans across Pennsylvania,” Schultz said in an interview with The Inquirer. “That is why you see people coming out more and more in support of Josh Shapiro.”

Chertoff was the second secretary of Homeland Security, following former Pennsylvania Gov. Tom Ridge. Ridge told the Harrisburg Patriot-News this week that Shapiro is a “very impressive man” and that he sees “a real distinct difference in the campaigns.” Ridge stopped short of saying he would vote for Shapiro, calling his ballot a private matter.

Other Republicans announcing their support for Shapiro on Tuesday include Mario Civera, a former state representative and former chair of the Delaware County Council, former Bucks County District Attorney David Heckler, and former State Reps. Raymond Blunt Jr. of Montgomery County, Jim Kelly of Allegheny County, Beverly Mackereth of York County, and J. Scot Chadwick of Bradford County.

Two Republican-run super PACs are already organizing advertising campaigns to draw GOP voters away from Mastriano in favor of Shapiro.

Republicans 4 Shapiro is run by former U.S. Rep. Jim Greenwood of Bucks County, who was among some of the first in his party to publicly endorse Shapiro. He has called Mastriano “an extreme, dangerous guy who is out of touch with the majority of the people in Pennsylvania.”

The Republican Accountability PAC is heading a national $10 million effort to oppose candidates identified as extremists in six states, including $2 million against Mastriano in Pennsylvania.

Mastriano, who limits campaign communications to supportive conservatives pundits, has claimed that a secret group of Democratic leaders in Harrisburg are pulling for his election. He has offered no evidence to support that claim.