The Democratic Senatorial Campaign Committee sent a memo to reporters today all but predicting Sen. Patty Murray won’t capture a majority in the primary and Republican Dino Rossi may wind up as the top votegetter.

“Given that Rossi received 46.35 percent in a crowded ten candidate field in the 2008 gubernatorial race, we expect him to earn at least that much in tomorrow’s primary,” DSCC executive director JB Poersch writes in the memo headlined: If History Teaches Us Anything…What Dino Rossi Should Receive in Tomorrow’s Primary

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Poersch figures Murray wins in November and cites an analysis of the 1998 election by Quinn McCord of Hotline to support his conclusion.

Here’s what McCord wrote:

Murray surely hopes her current race runs much like her 1998 one did. To be sure, there were some warning signs for her in Sept. of that year. In the ‘98 primary, she won just 45.9% of the vote, and the total Dem vote was only 48.4%. Meanwhile, four GOPers garnered a net 50.3%, with most of that split between then-Rep. Linda Smith (32.3%) and multimillionaire/ex-King Co. prosecutor Chris Bayley (14.9%). Nevertheless, come Election Day ‘98, Murray trounced Smith 58.4%-41.6%, representing a +10% swing in the net Dem vote and a -8.7% loss on the GOP side after just two months.

This swing towards Murray can be attributed to as many as four factors: The most obvious is that many Dem and independent primary voters chose to vote in the GOP race (mildly-contested as it was) rather than “waste” a primary vote for Murray, only to vote for the incumbent in the general election two months later.

The second is that the Washington general election electorate is always slightly more Dem than the state’s primary electorate. (In some cases, it may only be by 1% or so, but in the 10 federal elections of ‘98, Dem nominees benefited from a 4% boost on average from their party’s net primary votes.) This feeds into the third factor, which is simply that a mid-level Dem wave was building in the fall of ‘98 which grew more powerful between Sept. and Nov. of that year. The fourth factor, somewhat tied to the first, is that moderate voters who cast ballots for Bayley in the primary that year were unwilling to vote in Nov. for the more conservative Smith.”

By the way, when Murray first ran in 1992 there were 11 candidates. She finished with 28.3 percent of the total followed by Republican Rod Chandler with 20.3 percent.