Biden swears in Sen. Cowan

Rep. Ed Markey (D-Mass.) has announced that he will run in the special election. Former Sen. Scott Brown (R-Mass.) has said he won’t run.

Kerry, who attended the swearing in, left the Senate to serve in President Obama’s Cabinet as secretary of State. The Senate overwhelmingly confirmed Kerry for the position last week.

For more on Cowan's swearing in, click here.