Former U.S. Attorney Thomas Heffelfinger, a two-time Republican presidential appointee to the post in Minnesota, announced his support Tuesday for former Vice President Joe Biden in letters and in interviews with the Washington Post and the Star Tribune.

He was among 20 former U.S. attorneys appointed by Republican presidents from Eisenhower to Trump who signed the letter declaring their support for Biden and calling Trump a "threat to the rule of law."

Heffelfinger has a deep history with the GOP. In an interview Tuesday, he said he'd already cast his vote for Biden at Edina City Hall and couldn't be silent about his decision because of the importance of the presidential election. Heffelfinger's cited reasons include Trump's comments about Minnesota political leaders in the aftermath of the May 25 killing of George Floyd in police custody, Trump's use of the Justice Department to pursue political enemies and his misogyny.

Over the summer, the president's statements about the leadership of DFL Gov. Tim Walz and that of leaders in Minneapolis and St. Paul "made a tragic situation much worse," Heffelfinger said.

He didn't cite specific comments by Trump, but amid protests in the Minnesota, the president tweeted, "when the looting starts, the shooting starts," implying that protesters could be shot. Trump also urged political leaders to "dominate the streets."

In a statement first published Tuesday by the Washington Post, the former federal prosecutors said that Trump "has politicized the Justice Department, dictating its priorities along political lines and breaking down the barrier that prior administrations had maintained between political and prosecutorial decisionmaking."

Trump also has "undermined the Department's ability to unify and lead our nation's law enforcement by picking political fights with state and local officials in a naked effort to demonize and blame them for the disturbances in our cities over the past several months," the letter said.

Although they were political appointees, the former prosecutors who signed the letter said politics were not part of their decisions to sign it. This president, however, has used "prosecutors to serve his personal and political interests," their letter says.

In a commentary piece Heffelfinger said he submitted to the Star Tribune's editorial page, he wrote that he worries about what nonpartisan prosecutors would be asked to do on Trump's behalf in a second term. "He believes the Department should investigate and prosecute his political opponents," Heffelfinger wrote.

In contrast, Heffelfinger wrote, Biden has devoted his career to supporting law enforcement. Heffelfinger said Biden's commitment to the rule of law was underscored by his choice of Sen. Kamala Harris, a former district attorney and California attorney general, as his running mate.

"She recognizes the importance of independent, competent prosecutors," Heffelfinger wrote.

The Department of Justice will be called upon to help the country address "deep, structural issues and inequities that have long plagued our society," but that won't be possible if Trump is re-elected, he added.

In the Washington Post, Hogan Gidley, a spokesman for the Trump campaign, dismissed the joint statement of the former U.S. attorneys as arrogant and offensive, adding that Trump has the support of many police officers and their unions.

"No one should be surprised establishment elitists are supporting Joe Biden," Gidley said.

In Heffelfinger's interview with the Star Tribune, he traced his disdain for Trump back to the Access Hollywood tape that became public in October 2016 during his campaign against former U.S. Sen. Hillary Clinton.

Heffelfinger called the tape "inexcusable" and "obscene," and he questioned how Trump could be a leader of the women in the country. "How can you be president of the United States when you make comments like that about groping women and you laugh about [it]?"

Heffelfinger said he still considers himself a Republican in the style of moderates like former U.S. Sen. Dave Durenberger and former Gov. Arne Carlson. A fundamental difference between Biden and Trump is "decency," he said.

Others who signed the letter include William H. Webster, prosecutor for the Eastern District of Missouri from 1960-1961 who also served as director of the CIA and the FBI; Jonathan L. Goldstein, New Jersey 1974-1977; Matthew Orwig, Eastern District of Texas 2001-2007; and Stanley Twardy, District of Connecticut 1985-1991.

Heffelfinger was appointed U.S. Attorney in Minnesota by President George H.W. Bush in 1991 and again by President George W. Bush in 2001. He resigned in February 2006, nearly six months before the first of eight U.S. attorneys were sent packing in a widespread purge.