Iowa Representative Steve King wants to fight the Treasury Department's plan to put 19th-century abolitionist and suffragist Harriet Tubman on the $20 bill.

King, a Republican who opposes affirmative action and has expressed concern that white men are being excluded from politics, introduced an amendment on Tuesday that would block the Treasury from spending money on redesigning currency.

If his amendment goes through, it would quash the plan to replace Andrew Jackson, the seventh US president and a slaveholder, with Tubman, a black woman born into slavery who led dozens of former slaves to free states through the Underground Railroad.

"It's not about Harriet Tubman, it's about keeping the picture on the $20," King explained on Tuesday, according to Politico, while pulling out a $20 from his pocket and gesturing at Jackson's face. "Y'know? Why would you want to change that? I am a conservative, I like to keep what we have."

He added that the Treasury's plan — which would make Tubman the first black American and second woman to appear on US paper currency — was both "racist" and "sexist."

"Here's what's really happening" King said. "This is liberal activism on the part of the president that's trying to identify people by categories, and he's divided us on the lines of groups. ... This is a divisive proposal on the part of the president, and mine's unifying. It says just don't change anything."

King's concerns about revamping US currency were echoed by Donald Trump, the GOP's presumptive nominee, who dismissed the idea as "pure political correctness."

"Andrew Jackson had a great history, and I think it's very rough when you take somebody off the bill," Trump said during an interview on NBC's Today Show.

"I think Harriet Tubman is fantastic," he added. "I would love to leave Andrew Jackson and see if we maybe could come up with another denomination. Maybe we do the $2 bill or we do another bill... I think it would be more appropriate."

When Treasury Department Secretary Jack Lew announced the plan in April, he also said the back of the $5 bill will change to "depict civil rights leaders," while the front would keep the image of Abraham Lincoln. Leaders of the women's suffrage movement will appear on the back of the $10 bill.

According to data from the site SurveyMonkey, 56 percent of Americans support the Treasury's plans. The site also found that 80 percent of black Americans are in favor of the decision, compared to just 51 percent of whites.

Approval of Harriet Tubman on $20: 80% among African Americans, 61% among Hispanics, and 51% among whites ... new from — Jon Cohen (@jcpolls)April 21, 2016