Ms. Adams, low on cash, has not run a single campaign commercial. But a host of outside groups have swept in to swamp Ms. Kosmas with attack ads, helping establish Ms. Adams as the favorite without her having to spend on television.

Many of the conservative groups say they have been trading information through weekly strategy sessions and regular conference calls. They have divided up races to avoid duplication, the groups say, and to ensure that their money is spread around to put Democrats on the defensive in as many districts and states as possible — and, more important, lock in whatever gains they have delivered for the Republicans so far.

“We carpet-bombed for two months in 82 races, now it’s sniper time,” said Rob Collins, president of American Action Network, which is one of the leading Republican groups this campaign season and whose chief executive is Norm Coleman, the former senator from Minnesota. “You’re looking at the battle field and saying, ‘Where can we marginally push — where can we close a few places out?’ ”

Democrats said the conservative groups were upending some of their best-laid plans in several important races, like here in Florida, especially those in which they had been counting on the financial advantages their candidates had over lesser-financed Republicans at the beginning of the general election.

Filings with the Federal Election Commission over the weekend show that one Republican group, American Future Fund, has purchased more television advertisements attacking Representative Bruce Braley, Democrat of Iowa, who was expecting an easier path to re-election. Another group, the 60 Plus Association, reported spending more than $150,000 against Representative Solomon P. Ortiz, Democrat of Texas, who has been considered a likely victor in November against his cash-short challenger, Blake Farenthold.