FACTBOX-U.S. Senate races going Democrats' way

(Reuters) - With the economic crisis hurting Republicans in the elections on Tuesday, Democrats were building strength in the Senate but were unlikely to attain the 60-seat super majority they sought in the 100-seat U.S. Senate.

Holding 60 seats would have given Democrats the muscle to pass legislation in spite of Republican procedural hurdles. But a nine-seat gain appeared to be out of reach, according to senior Democratic aides in the Senate.

Overall, 35 Senate seats were up for election -- 23 held by Republicans and 12 by Democrats.

On the other side of the U.S. Capitol, Democrats were expected to pick up around 25 seats in the House of Representatives, which they now control 235-199. All the 435 House seats are up for election

Here's a look at projected results in key Senate races as well as a number of unresolved contests:

ELECTION RESULTS:

* Democratic Rep. Tom Udall won a U.S. Senate seat in New Mexico, replacing Republican Sen. Pete Domenici, who retired.

* Another Democrat, Rep. Mark Udall, who is Tom's cousin, was projected to win the Colorado Senate seat to replace Republican Wayne Allard, who retired.

* Democrat Mark Warner, a popular ex-governor, won in Virginia, capturing a Senate seat held by Republican John Warner, who also is retiring.