DES MOINES, Iowa (Reuters) - Republican White House hopefuls Herman Cain and Mitt Romney are in a tight race in Iowa, which kicks off next year's presidential nominating contests, according to an opinion poll published on Saturday.

The poll conducted for The Des Moines Register showed Cain, a businessman, with the support of 23 percent of Republicans surveyed, Romney, a former Massachusetts governor, with 22 percent, and Representative Ron Paul with 12 percent.

Texas Governor Rick Perry, who has stumbled on the campaign trail after a fast start, scored only 7 percent support.

The Iowa caucuses will take place on January 3, the first of the state-by-state contests to choose a party presidential nominee.

The Iowa Poll was conducted Sunday through Wednesday for the newspaper by Selzer & Co of Des Moines. The poll was based on telephone interviews with 400 likely Republican caucus- goers. The margin of error was plus or minus 4.9 percentage points.

(Reporting by Eric Johnson; Editing by Greg McCune)