Rep. Todd Akin reaffirmed for the final time today that he will be the irrevocable Republican Senate nominee in Missouri, despite the best efforts of national Republicans to get him to step aside after he made now-infamous comments about “legitimate rape.”

At a press conference in St. Louis, where he didn’t take any questions, Akin pledged to push forward in the face of today’s 5 p.m. CDT deadline to remove himself from the ballot.

National Republicans have refused to support Akin ever since he made the widely publicized comments about rape in August, with both the National Republican Senatorial Committee and Republican National Committee saying they will stay out of the race as long as he stays in.

Akin faces Democratic Sen. Claire McCaskill, who began the cycle as one of the most vulnerable Senators up for re-election. With it now clear that Akin will be on the ballot in November, Roll Call is changing its race rating for the Missouri Senate race from Tossup to Leans Democratic.

The Show-Me State is so favorable to a Republican that with an infusion of third-party cash, Akin could still have a shot. But by every measure, this race now favors McCaskill.

At today’s press conference, Akin compared himself to Harry  Truman in 1940. Democratic Party leaders tried unsuccessfully to defeat Truman in the primary that year, with President Franklin Roosevelt backing Missouri Gov. Lloyd Stark.

“In 1940, Harry Truman was pitched overboard by the Democrat Party in St. Louis and Kansas City, but he decided that he was going to challenge those particular leaders and let the public decide in the state of Missouri. The rest is history,” Akin said. “We’re going to do it again!”

But Missouri Democratic and Republican insiders see Akin as a weak candidate. He has never been a particularly strong fundraiser, making the support of national groups such as the NRSC and GOP aligned outside groups, such as American Crossroads, all the more significant. Even if some smaller groups come in to support him — and there are indications that some will — Akin and his allies are likely to be vastly outspent by McCaskill and her allies.

McCaskill is likely to hammer the lawmaker not just for his comments on rape, but also for his position on a slew of other issues from federal subsidies for school lunches to government-backed college loans to Medicare, Social Security and the minimum wage.

Akin argues that his views are more in line with Missourians than the first-term Senator on issues ranging from gun control to health care. He also criticized those who say the most fundamental question is about his ability to win.

“There’s another question that’s more fundamental, that is: What’s the right thing to do?” Akin said. “There’s an amazing correlation, when you do the right thing, you end up winning anyway.”

A savvy campaigner, McCaskill is widely credited in political circles with helping boost Akin during his GOP primary with negative ads that weren’t really negative. He won the Aug. 7 race against two strong competitors by about 6 points.