OKLAHOMA CITY (AP) - Republicans Mike Huckabee and Fred Thompson filed Wednesday for the Feb. 5 presidential primary in Oklahoma.

Huckabee, an ex-governor from neighboring Arkansas, and Thompson, a former U.S. senator from Tennessee, are expected to be strong contenders in Oklahoma, in which the primary will coincide with primaries and caucuses in 22 other states.

Huckabee has emerged as the main challenger to Romney in next month's Iowa caucuses.

Also filing before the end of a three-day filing period were Democrats Chris Dodd and Jim Rogers and Republican Daniel Gilbert of North Carolina.

Dodd is a senator from Connecticut and Rogers is a retiree from Oklahoma.

All of the major candidates in the Democratic and Republican fields will be on the Oklahoma ballot.

Those filing earlier in the week included Democrats Hillary Clinton, John Edwards and Barack Obama and Republicans Rudy Giuliani and Mitt Romney.

Edwards finished a close second to retired Army Gen. Wesley Clark in the Democratic primary in Oklahoma four years ago.

Most of the candidates had surrogates file their paperwork at state Election Board headquarters at the Capitol, or mailed in their declarations of candidacy and $2,500 filing fees.

An exception was Rogers, who filed in person and distributed a statement.

Rogers, who lives in the Oklahoma City suburb of Midwest City, lost two previous races for the U.S. Senate and one for lieutenant governor.

I lost and I decided I was doing it wrong. I'm going to start from the top and work down, the 72-year-old retiree quipped.

Rogers said he had sent inquiries to be a presidential candidate to a half-dozen other states, but did not qualify. He hopes to be a write-in candidate in some states.

He said the subprime lending fiasco poses the biggest economic threat to the country and must be solved to head off a recession or depression.

The winner of the Republican presidential primary will have inside track on winning in the November general election, based on recent history. A Democrat has not carried Oklahoma in a general election since 1964.