A new NBC News/Marist poll shows that Republican Sen. Ted Cruz is leading Democratic rival Rep. Beto O'Rourke by just four percentage points. Cruz has the support of 49 percent of registered voters polled, while O'Rourke has 45 percent.

Cruz leads O'Rourke among white voters, with the support of 67 percent of white voters without a college degree and 49 percent of white voters with a college degree. The college-educated white voter is quickly becoming a crucial demographic for Democrats, and if O'Rourke is able to cut into Cruz's support in that group, it could help to sway the election in his favor. Fifty-six percent of men also support Cruz.

Meanwhile, O'Rourke is the narrow favorite among independent voters, who back him 46 percent to Cruz's 45 percent. Latinos, women, voters under 45, and African-Americans also all support O'Rourke.

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No Democrat has won a statewide race in Texas since 1994, but progressives are hopeful that O'Rourke's barnstorming style of campaigning could attract new voters. O'Rourke's campaign raised over $10 million in three months, but the state remains more red than purple.

The poll also found that incumbent Republican Gov. Greg Abbott has the support of 56 percent of registered voters, while Democratic opponent Lupe Valdez has the backing of 37 percent. Abbott is defeating Valdez among almost every demographic.

The survey of 970 adults, including 759 registered voters, was conducted Aug. 12-16. The margin of error for registered voters is +/- 3.8 percentage points.