Republican U.S. Rep. Connie Mack III was making plans for his transition to the Senate Friday as Rep. Kenneth "Buddy" MacKay and Democratic Party officials considered a legal challenge to Mack's narrow victory.

MacKay refused to concede Thursday even after absentee ballots gave Mack a clear victory, saying he and his attorneys were discussing voting "irregularities" that he might challenge.Mack's victory decided the last of this year's 33 Senate races. It means the Democrats will have a 55-45 majority, a gain of one seat, in the new Senate.

Mack, who replaces retiring three-term Democratic Sen. Lawton Chiles, declared himself the winner when the absentee votes were announced.

"It's very exciting," said the 48-year-old grandson of the Baseball Hall of Fame manager. "It's been long; it's been tough. But I felt all along that my message of more freedom, free markets, freedom from taxes, freedom as an objective of our foreign policy, would come through clearly."

President Reagan, who did a television satellite feed for Mack's campaign Monday, called the Cape Coral congressman to congratulate him.

The AP's latest tally showed Mack with 2,044,575 votes, or 50 percent, to MacKay's 2,014,924 votes, also 50 percent. That gave Mack a margin of nearly 30,000 votes, more than enough to avoid an automatic recount.