Massachusetts Gov. Deval Patrick (D) has appointed his former chief of staff, Mo Cowan, to the Senate.

At a news  conference Wednesday morning, Cowan said he was confident he would make a difference in his short time in the Senate but had no plans to run for the seat in a June 25 special election. 

Patrick told reporters that Cowan has been a "professional colleague and a friend for a very long time" whose work helping Massachusetts through the financial crisis has prepared him well to serve in the Senate. He added that Cowan is also "cool," something Lt. Gov. Timothy Murray emphasized in his own remarks.

"Tom Brady, George Clooney, James Bond, the president have nothing on Mo," Murray said.

Cowan said he was "honored and humbled" by the appointment and "confident in my ability to make a positive impact for Massachusetts while I am in the Senate." He thanked his wife Stacy, "a true superwoman," his two sons and his mother, a single mother who grew up in the segregated South. "My mother told me days like today are possible," he said.

A native of North Carolina, Cowan is the first African American to represent Massachusetts in the Senate since Republican Edward Brooke held the seat from 1966 to 1978.

Cowan will replace Sen. John Kerry, who was confirmed Tuesday as the next secretary of state. He will serve as a placeholder until the special election can be held in June. Among the candidates expected to run for the seat are Reps. Ed Markey (D-Mass.) and Stephen Lynch (D-Mass.) Former senator Scott Brown (R-Mass.) has not announced his plans.

Cowan stepped down as as Patrick's chief of staff last month to pursue a private sector career. After the temporary appointment ends, that will still be his goal, he said; he is not a candidate for political office “today or any time in the future." The governor offered him the post yesterday, he said.

In picking Cowan, Patrick passed over other candidates, including former congressman Barney Frank (D-Mass.) and Vicki Kennedy, the widow of former senator Ted Kennedy (D-Mass.).

Cowan will become the second African American to join the Senate in the past month, along with South Carolina Sen. Tim Scott (R), another appointee. When he is sworn in, the Senate will feature two black members for the first time ever.

He can be followed on Twitter at @mocowan, and here is more on his background, from The Fix's Sean Sullivan.

Rachel Weiner contributed to this report.