John Bolton’s super PAC is backing Wisconsin Republican Senate candidate Kevin Nicholson by spending $1 million dollars on ads.

The former United Nations ambassador said he was supporting Nicholson for his service as a U.S. Marine and for serving in Iraq and Afghanistan. Nicholson is running in the GOP primary election against state Sen. Leah Vukmir. The winner of the primary will take on Democratic Sen. Tammy Baldwin in November.

“As a highly decorated U.S. Marine veteran who served in Iraq and Afghanistan, Kevin fundamentally understands what it takes to keep America safe," Bolton said in the statement.

"I know he will strengthen our military to eliminate ISIS and keep our adversaries at bay,” the statement added. “I support Kevin and look forward to him being the GOP nominee because he is best suited to support policies that protect the U.S. abroad and he can defeat Tammy Baldwin in 2018.”

Bolton said the contribution was part of a larger effort to help maintain a Republican majority in the Senate and was the first political contribution of 2018. After Democrat Doug Jones won the Alabama special election last month against Republican Roy Moore, Republicans only have a 51-49 majority in the upper chamber.

"This significant ad buy is a testament to my dedication to ensuring Republicans maintain the majority in the Senate this year. Kevin has my full support and I look forward to his leadership in Congress,” Bolton said in a statement.

A spokesman for the John Bolton super PAC, Garret Marquis, said Nicholson’s experience qualifies him to be a “leader in Congress.”

“The John Bolton Super PAC independently supports candidates, such as Kevin Nicholson, who can be leaders in Congress and are committed to restoring strong American economic and national security policies that secure America's interests in a challenging world," Marquis said.

Brad Bainum, spokesperson for the Democratic Party of Wisconsin, complained of "out-of-state special interests" who are not registered to vote in Wisconsin but are supporting Nicholson's run for office.

"Right-wing, out-of-state special interests are pouring millions into Wisconsin to buy Kevin Nicholson a seat in the U.S. Senate, where he's pledged to protect the corrupt Washington status quo,” Bainum said in a statement to the Washington Examiner. “Unfortunately for Nicholson, John Bolton, Steve Bannon and Illinois billionaire Dick Uihlein aren't eligible to vote in the Wisconsin Senate election."

Bolton served as the U.S. permanent representative to the United Nations during the Bush Administration in 2005 and 2006.