"We think that he adds definite competition to a position right now where we basically only had two guys here with Andrew (Walter) and Josh (McCown)," Raiders coach Lane Kiffin said.
"They've done extremely well but we needed to protect ourselves and make sure we're in the best position to win and make sure we have the most competition at that spot.
"He'll be part of that competition to be the starting quarterback. We'll give him the opportunity and see if he can take it and if he can't, he'll be a backup. "
Kiffin, who indicated negotiations with Russell had slowed over the weekend, spoke with the No. 1 overall draft pick by phone Tuesday morning and discussed the possibility that the team might sign Culpepper.
That they moved ahead with the deal is an indication the team is digging in for the long haul regarding Russell's negotiations.
"We'd like JaMarcus out here last week, but he's not so we have to go on as if he's not here right now," Kiffin said. "It's always important for your team to know things just as we informed both our quarterbacks last night that this was going to happen today, we were going to work him out today, make sure they heard it from us and understood the reasons we were doing it."
Kiffin was quick to point out that the signing of Culpepper was not just a ploy to pressure Russell and his agents into getting a deal done. On the contrary, the 6-foot-4, 265-pound Culpepper will practice Wednesday with his eye on starting.
"I know he's an effective quarterback because I've chased and hunted him over the years," Raiders defensive tackle Warren Sapp said. "If he's healthy, he's more than an effective quarterback. Somebody up top thinks he can help our ballclub, so let's see what we've got."