Republicans regained their lead over Democrats in Gallup's weekly generic ballot poll after falling back into a tie last week.

Forty-eight percent of registered voters said they prefer Republican congressional candidates compared to 43 percent who said they back Democratic office-seekers, according to the survey released Monday

Last week's tie represented the first time in the previous five weeks the GOP did not lead in the poll, which is a key indicator of voters' mood heading into election season. Poll results have been volatile: The week before last, Republicans held a 51-point to 41-point advantage over Democrats, a lead Gallup called "unprecedented."

Republicans continued to lead Democrats in voter enthusiasm measures. Ninety-six percent of Republicans said they would vote for a GOP candidate, the highest amount all year, compared to 90 percent of Democrats who said they would vote for a Democrat.

The number of Republicans who said they are "very enthusiastic" about voting in this year's congressional elections jumped 3 percentage points to 49 percent. Democratic enthusiasm also ticked up from 23 to 31 percent, but the party is still 18 points behind the GOP.

The poll, conducted between Sept. 6-12, has a 4 percent margin of error.