Fredreka Schouten

USA TODAY

As former President George W. Bush makes his return to the campaign trail Monday, a super PAC opposing Donald Trump is using his criticism of the nation’s 43rd president to attack the front-running Republican in South Carolina.

Our Principles PAC is funding digital ads that underscore Trump’s call in 2008 for Bush’s impeachment over the war in Iraq.

During Saturday night’s GOP debate, Trump fiercely criticized Bush’s handling of the war and questioned whether his policies kept the country safe. He kept up the criticism Sunday on CBS’ Face the Nation, calling the war “a disaster.”

Our Principles PAC, which has spent $3.3 million on anti-Trump efforts since it began operations in mid-January, also is distributing anti-Trump voter guides in the state.

The group’s move comes as George W. Bush re-emerges on the national political stage to help boost Jeb Bush’s campaign for the presidency. The former president is scheduled to appear on his younger brother’s behalf at a rally Monday night at the Charleston Convention Center. South Carolina's GOP primary is Saturday.

President George W. Bush seeks to rescue Jeb in South Carolina

Another group, the anti-tax Club for Growth, also is hitting Bush in the Palmetto State. The group is spending $1.5 million to air a 30-second television commercial that questions Trump’s conservative credentials.

Although establishment Republicans have fretted about Trump’s continued dominance in the GOP primary battle, Our Principles PAC and the Club are only two groups not affiliated with candidates that have spent big sums to oppose the real-estate magnate so far.

Trump and his aides have been harshly critical of both groups.

In an email to USA TODAY earlier this month, Trump spokeswoman Hope Hicks said Our Principles PAC had run “vicious and totally untrue attack ads” against Trump.

“Political action committees like Our Principles do the bidding of the few who benefit from the hard work of the many,” she added. “They hold the strings that make all the other politicians jump. They own the levers of power in Washington and cannot stand the thought that the people would actually want their government back.”