Given Congress' "fiscal cliff" agreement Jan. 1 and automatic spending cuts expected in March, Cowan said he backed a balanced approach to the nation's money problems that include some cuts and new revenues.
"I don't think anyone believes it's in the best interests to do straight across-the-board cuts," Cowan said, adding that such cuts would have "significant impact" on Massachusetts.
Some of the cuts could target grants to the state's highly regarded universities and research facilities.
Cowan will hold the office until voters decide June 25 on Kerry's successor. Already the race to fill Kerry's seat is shaping up.
Former U.S. Sen. Scott Brown, who lost his Republican re-election bid to Democratic Sen. Elizabeth Warren in November, is "leaning strongly" toward running in the special election, according to Republican officials. They spoke to The Associated Press on Tuesday on condition of anonymity because they were not authorized to share internal discussions.
Democratic Congressman Edward Markey of Malden has announced he's running for the seat, and U.S. Rep. Stephen Lynch of Boston, also a Democrat, is expected to announce his candidacy during a tour Thursday of the state. Kerry is among several leading Democrats who are backing Markey.
Cowan, 43, stepped down last month as chief of staff, a post he assumed in 2010 after previously serving as Patrick's chief legal counsel.
Patrick lauded Cowan for helping manage the state through the recession, and said Cowan had earned the respect of people throughout government.
"In every step, he has brought preparation, perspective, wisdom, sound judgment and clarity of purpose," Patrick said in announcing Cowan's appointment at a Statehouse news conference.
Patrick and Lt. Gov. Timothy Murray said the affable Cowan — who eschewed his trademark bowtie for the announcement in favor of a traditional suit and necktie — also brings a certain amount of "cool" to the job.
Cowan will be Massachusetts' second African-American senator. Edward Brooke, a Republican, served two terms from 1967 to 1979.
Cowan grew up in North Carolina and graduated from Duke University and from Northeastern University's law school. He was a partner in the prominent Boston law firm of Mintz Levin before going to work for Patrick, the state's first black governor.
Cowan noted Wednesday that his mother, who is recuperating in North Carolina after knee-replacement surgery, was a child of the segregated South who raised him and his sisters alone after his father died when Cowan was a teen.
White House spokesman Jay Carney said he believes President Barack Obama will be encouraged by Cowan's appointment, which coincides with a record number of female senators this year, "because he believes that diversity adds to the quality of debate."
In the days leading up to the selection, Patrick said he would consider diversity in his choice of interim senator. He also insisted the interim appointment be someone with no interest in holding the job permanently. And Cowan said Wednesday he had no intention of running for any elected office in the future.
"This is going to be a very short political career," he joked.
Former Democratic U.S. Rep. Barney Frank, who recently retired after more than three decades in the House, had been the only person to publicly express interest in the interim post and Patrick had acknowledged that Frank was among those he had considered.
Cowan's appointment marked the second time that Patrick has selected an interim U.S. senator. In 2009, following the death of Sen. Edward Kennedy, Patrick named Paul Kirk, a Democratic party operative and Kennedy family friend, to serve until a January 2010 special election, which Brown won.
Under Massachusetts law prior to 2004, governors appointed a senator to serve until the next regularly scheduled state election. The Democratic-controlled Legislature changed the law after Kerry became the 2004 Democratic presidential nominee to block then-Gov. Mitt Romney from appointing a Republican in case Kerry won the election.
Kerry's resignation from the Senate takes effect Friday, making Warren the state's senior senator despite having been in the Senate for only a few short weeks herself.