Washington state will hold top-two primaries today in each of its 10 House districts and to decide who will be the GOP’s sacrificial lamb this fall against Sen. Maria Cantwell (D). The state is expected to have just a couple of competitive House races in November.

The new Congressional map drawn by Washington state’s bipartisan redistricting commission solidified the incumbents who once represented competitive territory and transformed a Democratic stronghold into the most competitive district in the state. Reps. Rick Larsen (D), Dave Reichert (R) and freshman Jaime Herrera Beutler (R), who faced competitive races in 2010, were drawn into safer districts.

The state added a 10th district in reapportionment. Former state Rep. Denny Heck (D) is heavily favored to win the seat, which is based in Olympia’s Thurston County, in November. Washington holds its elections by mail. Therefore, all primary ballots must be postmarked by today or dropped at a ballot box location or county elections office by 8 p.m. local time today. Here are the races worth watching tonight:

House

1st District

The competitiveness of this potential swing district will depend in large part on which Democrat advances to the general.

Scant public polling has shown a dogfight — the leading Democrats are Suzan DelBene, a self-funder who lost to Reichert in 2010, and Darcy Burner, a liberal darling who lost to Reichert in 2006 and 2008. Other Democrats hoping to squeak into the top two include state Sen. Steve Hobbs and former state Rep. Laura Ruderman.

Gov. Christine Gregoire and Reps. Rick Larsen and Adam Smith endorsed DelBene, who bankrolled her primary campaign to the tune of $1.9 million and is unlikely to be outspent in the general. Should Burner, who is more liberal, or another Democrat, advance, both parties would likely alter their spending strategies to account for a more competitive general election.

As the lone Republican, John Koster, who lost to Larsen in the 2nd district in 2010, will take most of the GOP primary votes and is expected to advance.

This was redrawn as the state’s most competitive district after it became clear that former Rep. Jay Inslee (D) would vacate the seat to run for governor. Once a Democratic stronghold, it’s now split between the Democratic-leaning Seattle suburbs, which include the Microsoft campus, and a Republican-leaning agricultural area in three large counties to the north.

6th District

It will be hard to replace Rep. Norm Dicks (D), the Appropriations Committee ranking member who is retiring after 18 terms. But his exit inspired several Republicans to run for this Democratic-leaning district, which could be competitive for the GOP under the right circumstances.

Although a crowded Democratic field was expected, it essentially cleared with the entrance of state Sen. Derek Kilmer, who has proved to be a strong fundraiser. His most likely GOP opponent is businessman Bill Driscoll, who has invested $500,000 of his own money.

The race has the potential to get competitive. But, this being a presidential election cycle, the circumstances are not ideal for a GOP win.