Americans are practically split on whether they will vote for a Republican or a Democrat in November's midterm elections, the Gallup generic ballot poll released Monday found.

Forty-six percent of registered voters said they prefer Democratic congressional candidates compared to 45 percent who said they back Republican office-seekers, according to the poll. The 1-point span falls within the poll's margin of error, rendering the Democrats' lead statistically insignificant.

The results of Gallup's generic ballot poll, a key bellwether of congressional elections, have been volatile in recent weeks. Republicans opened up a 5-point lead last week after falling into its first tie with the Democrats in five weeks before that. The week before the previous tie, the GOP held a 10-point advantage over the Democrats, a lead Gallup called "unprecedented."

The overall results of the weekly poll have swung in Democrats' favor during the past two months. In August, Republicans edged Democrats 49-43 percent but in September, the GOP leads 46-45.

Republicans have consistently led Democrats in voter enthusiasm measures, an outcome that held firm this week. Forty-seven percent of Republicans polled who said they were enthusiastic about voting this fall noted they were "very" enthusiastic compared to 28 percent of Democrats who said so.

The poll, taken of 2,295 registered voters between Sept. 13-19, has a margin of error of 2 percentage points.