McCain Is Said to Be Set to Unveil Running Mate Tomorrow

McCain is solidly opposed to abortion rights, and nearly six in 10 of his supporters polled said abortion should be illegal in most or all cases.

In the telephone survey of 1,108 registered voters taken Aug. 19 to Aug. 22, which tested six possible vice presidential candidates, most said the choice of a running mate would not change their vote for president. That was especially true of lesser-known candidates: Pawlenty (86 percent); Florida Gov. Charlie Crist (83 percent); Sen. John Thune (S.D.) (81 percent) and Ridge (80 percent).

Of the six, Romney would generate the largest following -- 20 percent say adding the former Massachusetts governor would make them more likely to support McCain. But nearly as many -- 16 percent -- said they would be less apt to vote GOP with Romney on the ticket.

Lieberman would appear to do the most damage. Overall, about one in five voters said choosing the former Democrat would make them less likely to back McCain, more than the 12 percent who would be more inclined to support the GOP nominee. And perhaps more tellingly, among those currently supporting McCain, 22 percent said they would be less apt to support the GOP nominee if he picks Lieberman. Just 9 percent of those backing Obama would be more interested in voting Republican with Lieberman as the No. 2.

Democrats are already gearing up to attack McCain's vice presidential pick, no matter whom it might be. Progressive Accountability, a left-leaning advocacy group, has prepared a dossier on five contenders: Romney, Lieberman, Pawlenty, former Ohio congressman Rob Portman and Rep. Eric Cantor (Va.).

Each of the opposition research documents uses the identical header, naming the McCain ally in question next to the phrase "McSame as Bush."

Cillizza reported from Denver, Cohen from Washington. Staff writers Michael D. Shear in Sedona and Juliet Eilperin in Washington and polling analyst Jennifer Agiesta in Washington contributed to this report.