But several states hold contests on the same day.
Other states, including Massachusetts and Minnesota, will also hold contests that day.
Only the four traditional early starters Iowa, New Hampshire, Nevada and South Carolina were permitted to hold contests in February.
Now, Mr. Gingrich has pledged to take his campaign to Alabama and Mississippi, which will hold contests later this month.
Four other states will hold contests during the coming month: Colorado, Minnesota, Arizona and Michigan, where Mr. Romney's father was once governor.
Mr. Gingrich may be looking forward to a return to Southern states on Super Tuesday, when Georgia, Virginia and Tennessee hold contests.
(Hawaii and Illinois and the territories of Puerto Rico, Guam, the Virgin Islands and the Northern Marianas Islands will also hold contests in March).
Saturday 5 March: On Saturday, the Democrats hold contests in Kansas, Louisiana, and Nebraska, while the Republicans tussle over Kansas, Kentucky, Louisiana and Maine.
But the big prize comes a week later, on March 6, when 10 states hold contests, awarding a total of 437 delegates.
That will crest on March 6 — once again dubbed Super Tuesday — when 11 states hold contests for a total of 466 delegates.
