DES MOINES, Iowa (AP) — Mitt Romney is still the Republican to beat in Iowa, maintaining a lead he's held over other presidential candidates for months.

A poll released Sunday by The Des Moines Register shows the former Massachusetts governor with support from 29 percent of Iowa Republicans. Fred Thompson, the actor and former Tennessee senator, is in second place with 18 percent.

Romney has campaigned extensively in Iowa and has aired a steady stream of television ads.

Thompson scored well in polls of potential caucus-goers even before officially entering the race in September. The Register poll showed him holding onto second place but not cutting into Romney's lead.

Although Rudy Giuliani leads in national polls, he hasn't fared as well in Iowa and now is about even with Mike Huckabee in third place. The poll gave Huckabee 12 percent, up markedly since earlier in the summer. Giuliani had 11 percent and John McCain 7 percent.

The telephone poll was conducted Oct. 1-3 of 405 registered voters who said they would definitely or probably attend the Republican caucuses. It has a margin of sampling error of plus or minus 4.9 percentage points.