Iowa’s congressional delegation is split along party lines over a key proposal President Obama highlighted in his “State of the Union” speech.

Obama has proposed raising the tax rate to at least 30 percent for Americans who make more than a million dollars, an idea Omaha billionaire Warren Buffett advocates. Obama invited Buffett’s secretary to this evening’s speech in D.C., as Buffett often says he pays a much lower tax rate than his secretary does. That does not sway Steve King, a Republican Congressman from western Iowa.

“Warren Buffett has shielded a lot of income,” King says. “We can’t look at Warren Buffett’s tax rate and his secretary’s tax rate and draw any calculation…so it looks to me like it’s a political ploy more than anything else.”

Republican Senator Chuck Grassley says “under-taxing” millionaires and billionaires isn’t the problem.

“But the most important thing is the intellectual dishonesty of saying that Buffett’s paying 15 percent and that’s less than what his secretary pays. He pays 15 percent on capital gains, but you’ve got to remember that same money was taxed at 35 percent at the corporate level,” Grassley says. “You could figure that dollars taxed at 50 percent, not 15 percent.”

Republican Congressman Tom Latham of Clive doesn’t directly accuse President Obama of engaging in “class warfare,” but Latham’s no fan of raising the tax rate on the wealthy.

“I think it’s important that we try to unite the country and not divide the citizens economically or wherever,” Latham says, “because we’ve got a lot of problems in this country.”

Iowa’s three Democratic Congressmen all support the higher tax rate for people who make more than a million dollars. Congressman Bruce Braley, a Democrat from Waterloo, says over the past two decades federal tax policy has been “strongly skewed” in favor of “the wealthiest” Americans.

“The president’s powerful message about tax equity is something that most Americans support,” Braley says.

Congressman Dave Loebsack, a Democrat from Iowa City, says the wealthy should “contribute their fair share” in taxes.

“Everyone does have to pitch in, but it’s to make certain that the economy can move forward again,” Loebsack says, “that we can get people back to work again.”

Congressman Leonard Boswell, a Democrat from Des Moines, says he’s been a “long-time” supporter of raising the tax rate on top wage earners.

“Maybe amnesia set in how we got to where we are, but there’s no point in lamenting on it. We’re there,” Boswell says. “How do we get out of it? And if everybody participates and I mean everybody — all — we can do this.”

Senator Tom Harkin, a Democrat, says the Republican Party’s “trickle down” economics doesn’t work and Harkin argues Obama’s tax proposals “promote a better, more fair tax structure.”

President Obama is due to visit Iowa over the noon-hour Wednesday. He’ll give a speech at a manufacturing plant in Cedar Rapids, one stop in the president’s  swing through five “battleground states” in the November election. Conveyor Engineering and Manufacturing will also provide a backdrop to highlight the president’s proposals to boost the manufacturing industry.

(This story was updated at 10:56 p.m. to reflect Latham’s recent move from Ames to Clive, Iowa.)