In essence, Bradley thinks, and I concur, that Gore is an overambitious man who puts campaign positions ahead of governing and would do anything to be president. Both men have been willing to put aside partisan differences to pass bills. McCain sponsored a campaign finance bill that got widespread support from Democrats. Sen. Bradley's most notable accomplishment was the tax reform bill of 1986, which closed corporate tax loopholes and got widespread Republican support in addition to Democratic support. There is another side to their records, though.
Nobody can quite place their records on the current ideological spectrum.
Similarly, the Democrats don't know quite what to think of Bradley. He has a reputation as a moderate, and is getting more independent votes than Gore even though he runs on issues Gore is too timid to take on, issues that should seem to place him squarely in his party's liberal wing. However, groups like the unions, black voters and women ignore him. Beyond that, you can't quite quantify wanting to put dignity and trust back into the political process. It seems McCain and Bradley have broken the traditional mold.