U.S. senators traditionally don't pick favorites in contested primary races but to no one's surprise Ken Salazar is making an exception.

Salazar on Wednesday will officially endorse his former staffer, Betsy Markey, one of three Democrats running for Congress in 2008 in the 4th Congressional District.

Markey served as Salazar's regional director in the 4th District after the Denver Democrat was elected to the Senate in 2004. She resigned in May to run for Congress.

The endorsement will take place at 11 a.m. on the southeast corner of the state Capitol grounds.

Markey faces former state Rep. Angie Paccione, and Eric Eidsness, a former Reagan appointee who now is a Democrat. The winner will take on U.S. Rep. Marilyn Musgrave, R-Fort Morgan.

Paccione said today the endorsement was expected.

"Betsy worked for him for two and a half years," Paccione said.

Paccione, who nearly toppled Musgrave in a stunner two years ago, has always touted her status as an outsider among the party establishment.

She said she's after only after one endorsement: from the people of the 4th CD.

"If they want me to serve, I will serve with the greatest passion they've ever seen," she said.

Eidsness' supporters include former U.S. Rep. Jim Johnson, a Republican who once represented the 4th CD.

Pat Waak, chairwoman of the Colorado Democratic Party, agreed that it is unusual for a senator to endorse in a primary but said in this case, "Ken is real close to Betsy."

"He told me a while ago that she was considering running," Waak said.

Waak pointed out that Salazar is not endorsing in the 2nd Congressional District, where three Democrats also are vying for the nomination in 2008. The 2nd CD candidates are Senate President Joan Fitz-Gerald, conservationist Will Shafroth and entreprenuer Jared Polis.

The 4th Conressional District includes Fort Collins and the eastern plains.

The 2nd Congressional District includes Boulder and several mountain counties.

bartels@RockyMountainNews.com or 303-954-5327