Fred Thompson, a former Tennessee senator known as much for his role on "Law and Order" as for his work in Washington, is preparing a bid for the Republican presidential nomination.

Thompson would join a crowded GOP field, but polls indicate he would start in a strong position. Recent national surveys of Republican voters have shown Thompson with double-digit support, tied with or slightly ahead of Sen. John McCain. In most national surveys former New York Mayor Rudy Giuliani leads all GOP contenders.

Thompson has a dedicated band of supporters, many of them former Ronald Reagan activists, who have mounted a determined "Draft Fred" movement over the past several months.

Yesterday, Thompson financial backers said that on Monday they will register an exploratory committee with the Federal Election Commission. The move would allowThompson to begin raising money for a run at the White House. Thompson plans a Monday fund-raiser in Tennessee to coincide.

(UPDATE: UnionLeader.com learned Thursday afternoon from a New Hampshire Thompson activist that there will not be an FEC filing on Monday. Instead, a "testing the waters" committee will be established.)

Some Thompson supporters said he plans to officially announce his candidacy on July 4, but others said the date has not been set.

The FEC filing would come on the eve of a debate among 10 Republican candidates in New Hampshire. The New Hampshire Union Leader, WMUR and CNN are sponsoring the June 5 debate at Saint Anselm College, as well as a June 3 debate among eight Democratic candidates.

Union Leader vice president of editorial Charles Perkins said yesterday it is not necessarily too late for Thompson to join the GOP candidates on stage at Saint Anselm.

"Senator Thompson remains eligible for an invitation to Tuesday's debate if he announces an exploratory committee and meets the standards that apply to all candidates," Perkins said.

Former state Rep. Daniel Hughes said "a lot of people are excited about Fred Thompson and happy to see him join the race. He has a long and admirable record in the Republican party."

Hughes said that there is no formal state campaign organization in New Hampshire yet, but added, "I think you'll see it all come together during the next month."

Thompson is not the only candidate who has been seen as a potential late entry to the primaries. Former House Speaker Newt Gingrich and former Vice President Al Gore are considered possibilities.

The Thompson candidacy could be a blow to the campaigns of lesser-known Republicans who have struggled to get out of single digits in the polls, and to raise the cash to compete with better-funded candidates.

Andrew Smith, director of the University of New Hampshire Survey Center, said that among those who know Thompson, 29 percent have a favorable view of him. Even though 47 percent of likely Republican voters here didn't know enough about Thompson to rate him, Smith said, he likely enters the race among the top four candidates here.

Richard Killion, a political consultant with former Massachusetts Gov. Mitt Romney's campaign, said they'll continue unfazed. "The more the merrier," he said. "What the governor is doing and our staff is focused on is building a organization up to New Hampshire standards that will be tested and proven."

Romney has raised more than any other Republican candidate and leads in New Hampshire among likely Republican primary voters.