OAKLAND (CBS / AP) — The Oakland Raiders took big steps Thursday to shore up their defense before a potential lockout next week, placing the franchise tag on linebacker Kamerion Wimbley and agreeing to deals with potential free agent cornerback Stanford Routt and defensive tackle John Henderson.

The moves follow last week’s signing of defensive tackle Richard Seymour to a $30 million, two-year contract as Oakland has aggressively tried to lock up as many players as possible before the collective bargaining agreement expires March 3.

The Raiders also re-signed running back and key special teams contributor Rock Cartwright before he could become a free agent.

But the biggest moves have come on the defensive side of the ball after the Raiders allowed at least 30 points in six of their eight losses last season.

The team announced its decision to place the franchise tag on Wimbley, guaranteeing him a deal projected to be worth more than $10 million next season.

“Kamerion is a great young talent and he and the Raiders are excited about him continuing his career as a member of the Silver and Black,” coach Hue Jackson said.

The Raiders agreed with Henderson on an $8 million, two-year contract, sources told both the Associated Press and ESPN, although the deal had not yet been publicly announced.

Also, Oakland has agreed with Routt on a three-year, $31.5 million deal after his best season in the NFL, according to NFL.com and ESPN. The Raiders would not confirm the deal but made clear their desire to retain Routt.

“Stanford Routt is in his prime,” senior executive John Herrera said. “He’s a young, 27-year-old veteran, who already has six years of experience in the league. He’s one of the fastest cornerbacks in the league and his best years are still ahead of him.”

After slipping behind Chris Johnson on Oakland’s depth chart in recent years, Routt had his best season in 2010. Opponents completed just 39.4 percent of passes against Routt – one of the best marks in the league despite being a frequent target as teams stayed away from Nnamdi Asomugha’s side. He improved markedly from 2009, when he allowed opponents to complete 65.9 percent of their passes.

While Asomugha was targeted on just 33 pass attempts this season, allowing 13 completions for 205 yards and no touchdowns, Routt was targeted 99 times. The completion percentage against him was the lowest in the league of any player targeted at least 60 times and was comparable to the numbers put up by the more heralded Asomugha (39.4 percent) and the New York Jets’ Darrelle Revis (33.9 percent).

With Asomugha a free agent who might not return to Oakland after his $16.8 million option was voided, keeping Routt was a high priority.

The Raiders originally hoped to use a $3.5 million buyback option to keep Wimbley under contract for next season for just over $4 million.

But the NFL determined that deal violated rules prohibiting base salaries rising more than 30 percent in a year. That led to the Raiders decision to use the franchise tag, which is projected to be worth about $10 million.

Wimbley led Oakland with nine sacks last season after coming over from Cleveland in a trade for a third-round pick. Keeping him was a key priority this offseason for owner Al Davis.

“We look forward to working with Mr. Davis on a long-term deal,” agent Joe Linta said.

The two sides can negotiate until the collective bargaining agreement expires. Wimbley can also negotiate with other teams, but any team signing him would have to give the Raiders two first-round draft picks as compensation.

Henderson had 30 tackles in nine games last season for Oakland while being limited by a foot injury. Henderson, a two-time Pro Bowler in Jacksonville, played mostly as a reserve to shore up the run defense in his first season in Oakland last year.

Among the other key potential free agents for Oakland are tight end Zach Miller, running back Michael Bush, safety Michael Huff and offensive lineman Robert Gallery.

(© 2011 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)