Republicans maintained large leads over Democrats among likely voters in a key generic ballot poll released just over two weeks before Election Day.

In both high- and low-turnout models conducted by Gallup, Republicans held double-digit leads over Democrats for the third straight week. 

Republicans lead Democrats 56-39 percent in a low-turnout scenario and 53-42 percent in a high-turnout model, according to Gallup's poll. 

The poll suggests that the GOP is poised to make large inroads on the Democrats' majorities in Congress on Nov. 2. Democrats have claimed that they have made progress in terms of voter enthusiasm over the past few weeks, with President Obama headlining heavily-attended rallies in key states to rally support among young voters.

But Democrats have failed to make up ground overall against Republicans in the poll, which is considered a bellwether of the outcome on Election Day. 

Still, Democrats are planning to put up a stiff effort up until Nov. 2 in order to maintain their majorities. President Obama and Vice President Joe Biden are planning to travel to Washington, Nevada, Ohio, Maryland, Oregon, California and Minnesota over the next week to campaign for House, Senate, and gubernatorial candidates. 

Gallup conducted its poll, which has a three percentage point margin of error, between Oct. 7-10 and Oct. 14-17.