...Washington— After locking up much of the Republican establishment's heavyweight fundraisers, Mitt Romney is going after the little guy. "Donate $3 today to be automatically entered to be Mitt's special guest for Election Night on Super Tuesday," reads an email appeal from the Romney campaign to supporters. A dramatic new Web video asks for $20 contributions to fight the "Obama Attack Machine." The GOP presidential candidate made a similar solicitation after clinching the Michigan primary Tuesday, with a rare personal plea for people to visit his website and "pledge your support — in every way possible." The pitch reflects a...