The men, both from Sangamon County, spoke Saturday at the Edwardsville Public Library as part of a forum sponsored by the League of Women Voters of the Edwardsville Area.
"I'm 26 years old. Young some say," Davis began, "But I tell you what, I've got all the passion one person can have to make a difference. And I've got all the energy in the world to go out there and do something about it."
Recently Davis served as assistant to the director of the Illinois Department of Public Health. Before that he worked there as a legislative liaison.
McMenamin stressed his experience as an attorney and as a war veteran.
He has practiced law for 28 years, and also served for seven years in the Illinois Army National Guard, including a 12-month stint in Afghanistan in 2004 and 2005.
In his introductory remarks, McMenamin characterized the Iraq War as a tragic mistake. "It'll go down as the most significant foreign policy blunder in our nation's history," he said. "Instead of investing in America, we have squandered our resources overseas."
McMenamin said that he decided to run because the country is "seriously off track."
He drew the first chuckle of the two-hour forum when he recounted how he went door-to-door last weekend and asked residents "how off track we area, on a scale of 1 to 10."
"Often they would say, 'Can I go any higher?'"
Davis told the most poignant story when he talked about a woman who sent him a check despite her husband's impending layoff at the coal mine. "But we believe in you so much, we're going to send $25, and we're going to hold on to your address so that when we can, we'll send some more."
Davis favors spending limits for federal candidates.
McMenamin claimed that when he decided to run for the 19th Congressional District, Shimkus already had "a million dollars at his disposal."
He criticized Shimkus for running for Congress again this year despite a pledge in 1996 that he would not stay in office for more than 12 years.
Shimkus has since said that making the pledge was a mistake.
"He's a West Point graduate, and he knows the sacredness of pledges," McMenamin said. "So now I'm running to honor his pledge."
The winner of the Feb. 5 primary will meet Shimkus in the general election in November.