His continued presence is going to harm them for the rest of the election.
His continued presence will continue to remind voters that many other Republicans, beside Akin, think about these issues in the same way he does. And that definitely includes Paul Ryan. While Ryan has currently been forced into saying, "Rape is rape, end of the story," his past track record on the issue speaks for itself, and it's not the end of the story. A vote for Romney is a vote that could potentially put Paul Ryan in the White House.
All Akin did was to let the cat out of the bag in terms of the many other religious right wing Republicans who share the same views, and that base has significant influence on party policy, and party votes in Congress, and the type of legislation that will affect everyone. Better that the general public realizes now what these people are like, how they think, and wake up to the fact that Romney is cut from the same cloth and more than willing to pander to that extremist segment of his party's base.
I think Akin's remarks will wind up doing the country a favor by shining a light on the unsavory underbelly of the Republican party.