McGovern's plan is not entirely unlike the Democratic plan in the Senate for a "phased redeployment" of U.S. troops from Iraq. Sen. Carl Levin, who will chair the Armed Services Committee starting in January, has said that the United States "cannot save the Iraqis from themselves" and that "political will" is the missing ingredient in Iraq.
The various Democratic withdrawal plans all argue that the U.S. presence there is no longer helping the situation, but they all agree that leaving is a gamble.
"Do we think everything is going to be hunky-dory after we leave? No," McGovern said. "We don't know what's going to happen. But we think we remove the principal irritant" when the U.S. troops withdraw.
McGovern argued that the United States could save money on reconstruction by contributing "3 percent of the hundreds of billions that the United States is going to pay to keep a large army there."
For their book, Polk said he studied 12 conflicts throughout history and found that there is a clear pattern.
"In every case, when the principal occupying force pulled out its army, the fighting subsides," he said.
McGovern and Polk were originally supposed to meet with a much larger group of progressive Democrats, but the caucus got in the way. They plan to return to the Hill sometime in January.
ABC's Dalia Sussman contributed to this report.