Charlotte, NC (SportsNetwork.com) - Michael Waltrip Racing announced on Tuesday that David Ragan will drive the No. 55 Toyota for the remainder of the 2015 Sprint Cup Series season, beginning with the May 9 race at Kansas Speedway.

Brian Vickers was to drive the No. 55 car for MWR this year, but open heart surgery in December forced Vickers to miss the first two races of the season. He returned to racing for the March 8 event at Las Vegas, but two weeks later when the series competed in Fontana, California, he was sidelined by recurring blood clots in his lungs.

Vickers is currently taking blood-thinning medication, preventing him from being able to race. No timetable has been set for his return.

Team co-owner Michael Waltrip is scheduled to drive the No. 55 in this weekend's race at Talladega. Brett Moffitt drove it in six races this season. Moffitt finished a career-best eighth at Atlanta on March 1.

Ragan had been driving the No. 34 Ford for Front Row Motorsports, but after the Feb. 22 season-opening Daytona 500, Ragan moved over to Joe Gibbs Racing to substitute for the injured Kyle Busch in the No. 18 Toyota. Busch suffered a fractured right leg and left foot during an accident in the Xfinity Series season-opener at Daytona.

"Life has thrown a lot at MWR the first part of this racing season, but our team has stood tall and worked through it," Waltrip said in a team statement. "Our original plans for the No. 55 team have been challenged since December, and we felt it was important for our employees and our sponsors to solidify the remainder of the 2015 season. The opportunity to bring David Ragan into the team is incredible for a number of reasons. He will bring experience, consistency and a lot of confidence based on how he has been running with our Toyota teammates at Joe Gibbs Racing. He also puts the No. 55 team and Aaron's (team sponsor) right back into the Chase for the Sprint Cup contention, which is a very positive turn of events for that team."

Vickers drove the No. 55 in a partial schedule during the 2012 and '13 Sprint Cup seasons and then ran a full schedule in 2014. He finished 22nd in the point standings last year, with three top-five finishes and 9 top-10s for the season.

"There is absolutely no question about Brian Vickers' ability, but there remains a question of his availability," Waltrip added. "We are going to remain very close with Brian while he works on his plan to return. We have told him that MWR is here when he has a clear picture about what the future holds, but we don't need to add any timeline pressures. He is working with a lot of medical advisors, and once he has established his plan, we will sit down and discuss next steps."

Ragan has driven the No. 18 car for JGR in eight races this season, beginning with Atlanta. He is presently 19th in points, with one top-10 finish (fifth place at Martinsville). Ragan is scheduled to drive the 18 for the final time this weekend at Talladega. It will be his 300th career start in the series.

"The only way I can repay all the people I have to thank for making this happen is to go out and win races and get MWR, Aaron's and Toyota in the Chase," Ragan said. "It's going to be awesome knowing when I climb in the No. 55 at Kansas that car will be mine the rest of the season. I look forward to working with (teammate) Clint Bowyer, the crew and shop employees at MWR. It's tough what's happened to them this year, but I hope I can come in and make 2015 something special."

Ragan has two wins in the series -- July 2011 at Daytona and May 2013 at Talladega.

JGR has yet to announce their driver plans for the 18 car for Kansas and beyond, but there is wide speculation that 18-year-old Erik Jones might take over that ride until Busch returns. Busch is hoping to be back in the car in July.

Chris Buescher, a regular in the Xfinity Series, will drive the No. 34 car for Front Row at Talladega. The team said in a news release on Tuesday that it is working on finalizing the driver lineup for races to follow and will announce those plans soon.