AUSTIN -- A new poll by the University of Texas and the Texas Tribune shows Republican Ted Cruz ahead of Democratic challenger Beto O'Rourke by 6 percentage points in the Texas Senate race, a week and a half before Election Day.

In a poll of likely voters conducted before the start of early voting this week, 51 percent of voters favored Cruz, while 45 percent favored O'Rourke. Two percent said they'd vote for Libertarian candidate Neal Dikeman and another 2 percent said they were undecided.

Among independent voters, O'Rourke was up 51 percent to 39 percent for Cruz.

The race is one of the most closely watched — and the most expensive — in the country. O'Rourke has motivated Democrats by barnstorming campaign across all of Texas' 254 counties and accusing Cruz of being an absentee senator more focused on running for president than representing the state.

Cruz has defended his record in the Senate and cast O'Rourke as a far-left socialist whose policies are out of touch with Texans.

The internet survey polled 1,200 registered voters and was conducted between Oct. 15 and Oct. 21. The margin of error was 2.83 percentage points. Among the likely voter sample of 927 people, the margin of error was 3.22 percentage points.

Polls this month had put O'Rourke within 5 percentage points. But as Election Day draws closer, the gap between the two candidates seems to be growing. A Quinnpiac University poll put Cruz up 54 to 45 percent with a margin of error of 4.4. A poll by The New York Times and Siena College had Cruz up 51 to 43 percent with a margin of error of 3.6 percentage points. CNN had Cruz up 52 to 45 percent with a margin of error of 4.5 percentage points.

The other major Republican candidates for statewide office all had double-digit leads on their opponents.

Gov. Greg Abbott was up nearly 20 percentage points on his Democratic opponent, former Dallas County Sheriff Lupe Valdez. Fifty-six percent of voters favored Abbott over Valdez's underdog campaign, which has support from 36 percent of voters.

Lt. Gov. Dan Patrick also held a commanding lead over his Democratic challenger, Mike Collier. Fifty-three percent of voters favored Patrick, while 35 percent favored Collier.

Attorney General Ken Paxton, who has been indicted on suspicion of securities laws violations, led challenger Justin Nelson by 48 percent to 36 percent.