(CBS)  Even after Sen. John McCain named her as his running mate on Friday, Alaska Gov. Sarah Palin remained an unknown quantity to most Americans. Sixty-six percent had no opinion of her in a CBS News poll conducted over the weekend. In polling completed on Monday and Tuesday, sixty percent still had no opinion about her.

But of those who did have opinions, 26 percent of the most recently polled were favorable, while only 13 percent were not favorable.

More than one in four voters said that the vice presidential choices will matter this year, but few voters say that having Palin on the Republican ticket will change their vote. Just 14 percent said they are more likely to vote for McCain as a result of having Palin on the ticket, while 13 percent said they are less likely to do so. Sixty-eight percent said it won’t make a difference in their vote.

Seventy-four percent of voters said the addition of Joe Biden to the Democratic ticket made no impact on how they will vote. But those who said Barack Obama's choice mattered to them were three times as likely to say that Biden will make them vote for Obama rather than against him.

Read The Complete Poll

---

This poll was conducted among a random sample of 613 adults nationwide, including 540 registered voters, interviewed by telephone September 1-2, 2008. Phone numbers were dialed from RDD samples of both standard land-lines and cell phones. The error due to sampling for results based on the entire sample could be plus or minus three percentage points; for registered voters the sampling error could be plus or minus four percentage points. The error for subgroups is higher.

©MMVIII, CBS Interactive Inc. All Rights Reserved.