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 today 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 Eids-ness, a former Reagan appointee who now is a Democrat. The Democrats' pick will take on U.S. Rep. Marilyn Musgrave, R-Fort Morgan.

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

Her campaign manager, Steve Welchert, said Salazar's announcement actually helps Paccione.

"The woman who came closer to winning the 4th CD than any Democrat in 34 years is now assuming the role of underdog," Welchert said. "I couldn't have written a better script myself."

Paccione said Tuesday that she's after only one endorsement: from the people of the 4th District.

"I'm not good at kissing the ring, but I am good at representing the people," Paccione said. "If they want me to serve, I will serve with the greatest passion they've ever seen."

Eidsness said he "clearly" is the non-establishment candidate in the race.

The former Republican ran against Musgrave two years as a Reform Party candidate, winning 11 percent of the vote.

"When I get the nomination, I am certain Sen. Salazar will support me," he said.

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 District candidates are Colorado Senate President Joan Fitz-Gerald, conservationist Will Shafroth and entrepreneur Jared Polis.

The 4th Congressional District includes Fort Collins and the plains.

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

bartels@RockyMountainNews.com or 303-954-5327