Among the Republican seats in play:

• Alaska, held by Republican Sen. Ted Stevens. Stevens remains an icon in Alaska politics, but his son has been caught up in a scandal, and Democrats wonder whether Stevens, 85 in November, might opt to retire before the Aug. 26 primary. The likely Democratic challenger is Mark Begich, the mayor of Anchorage.

• Colorado, open seat being vacated by the retirement of Sen. Wayne Allard. The Democrat is Rep. Mark Udall, heir to a famous family name in Western politics, who's benefiting from a strong Democratic tailwind in the state. His party has captured the governor's office, the state Legislature and the other U.S. Senate seat. The Republican is former Rep. Bob Schaffer.

• New Mexico, open seat being vacated by retirement of Republican Sen. Pete Domenici. The state has trended toward the Democrats on the local level, holding the governor's office and other Senate seat by comfortable margins. The Democrat likely will be Rep. Tom Udall, heir to the same influential family name as his first cousin Mark in Colorado. The Republicans haven't picked a candidate — Reps. Steve Pearce and Heather Wilson are competing in the June 3 primary.