Poll: Donald Trump more than doubles his lead nationally

Donald Trump has more than doubled his lead nationally in the GOP presidential race, according to an NBC News/Wall Street Journal poll released Thursday ahead of the sixth Republican debate.

A third of GOP primary voters said they support Trump, while Sen. Ted Cruz, R-Texas, trails him in second place with 20 percent support. Trump has expanded his lead over Cruz by 8 percentage points since the last poll was conducted last month.

In the latest survey, 13 percent said they back Sen. Marco Rubio, R-Florida, and 12 percent said they prefer Ben Carson. New Jersey Gov. Chris Christie and former Florida Gov. Jeb Bush were tied at 5 percent while all of the other contenders did not receive more than 3 percent support.

The poll found the number of GOP primary voters who say they could see themselves supporting Trump has grown significantly. In March, less than a quarter said they could support them and nearly two-thirds say they could now.

In a three-way race between the top candidates in the new poll, 40 percent said they'd back Trump, 31 percent said they would vote for Cruz and 26 percent said they'd support Rubio. In a hypothetical three-way contest between Trump and Cruz, Cruz would actually defeat Trump 51 percent to 43 percent.

A CBS/New York Times national poll released this week found Trump is holding onto the top spot in the GOP presidential race. More than a third of GOP voters said they support Trump, Sen. Ted Cruz, R-Texas, came in second place with 19 percent support and Sen. Marco Rubio, R-Florida, trailed behind in third place with 12 percent support.

The poll surveyed 400 Republican primary voters between Jan. 9 and 13 with a 4.9 percentage point margin of error.