A new Elway Poll on the Senate race has incumbent Democrat Patty Murray up 50-41% over Republican challenger Dino Rossi.

The poll of 500 likely voters showed Murray's support strongest is among Baby Boomers, women and retirees.

Rossi has a big edge in Eastern Washington, Pierce and Kitsap counties, and with voters earning more than $75,000. He also leads among independents.

The Elway poll, released Monday, has a margin of error of plus or minus 4.5 percent.

Those results are quite a bit different from a KING 5 poll by Survey USA last month, which had Rossi ahead 52-45.

That poll, as Seattle PI.com's Chris Grygiel noted, weirdly had Rossi tied with Murray in the greater Seattle area, even though she won 59% of the King County vote in the primary. The Elway poll puts Murray's King County lead at 61-30%.

A Sept. 2 Rasmussen poll put Rossi ahead 48-46.

Meanwhile, a poll for the Democratic Senatorial Campaign Committee last week said Murray was up 50-45.

Stuart Elway offers a word of caution in his memo to poll subscribers:

"Although Murray is at 50% in this survey, there are enough "soft" supporters for each candidate, plus undecided voters and supporters of other candidates -- not to mention time on the calendar -- to determine the eventual outcome."

Still, Elway notes, if Rossi takes three-quarters of the undecideds in this poll, Murray would still lead 52-48%.

"Any way these data are sliced, victory for Dino Rossi requires that he take votes away from Murray. And you thought this campaign has been hard hitting so far," Elway writes.

Note: The Seattle Times and the Spokane Spokesman-Review teamed up to pay for additional polling by Elway to measure voter attitudes and opinions on important issues as we head toward election day.

Look for the results of that polling in Sunday's newspaper.