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Former U.S. Defense Secretary Donald Rumsfeld has sparked a small political skirmish by giving the maximum donation to U.S. Sen. Ron Johnson.

Records show Rumsfeld -- the architect of the wars in Iraq and Afghanistan -- has given two donations totalling $5,400 to Johnson in the first-term Republican senator's campaign against former U.S. Sen. Russ Feingold. Rumsfeld wrote checks in April 2015 and on March 21.

Rumsfeld made an earlier $1,000 contribution to Johnson in 2010, when he knocked off Feingold, a third-term Democrat.

"Sen. Johnson has accepted more than just checks from Donald Rumsfeld," said Michael Tyler, spokesman for Feingold. "He’s fully endorsed Rumsfeld’s reckless foreign policy agenda that only puts more American lives at risk."

Tyler said Johnson wants to repeat some of Rumsfeld's past mistakes in the Middle East by calling for an American-led ground invasion to drive the Islamic State of Iraq and Syria out of those two countries.

Johnson has called for "boots on the ground" to combat ISIS as early as October 2014 but he has been vague on the numbers, saying he favors a coalition of foreign and American troops. He told Mike Gousha that he has heard experts say the effort would require 100,000 troops, including 25,000 from the U.S.

Brian Reisinger, spokesman for Johnson, said Feingold is making a big deal out of the Rumsfeld contributions because he "knows he’s dangerously weak on national security." Reisinger specifically criticized Feingold for supporting the Obama administration's recent nuclear deal with Iran.

"Americans from all walks of life who are worried about our security are getting involved in this race to support Ron," Reisinger said. "There’s a lot at stake."