Democratic U.S. Senate candidate Beto O’Rourke is running about even with U.S. Sen. Ted Cruz in his bid to unseat the incumbent Republican, according to a poll of likely Texas voters released today by Reuters and Ispos in conjunction with the University of Virginia Center for Politics.

The poll shows a narrow 2 percentage point lead for O’Rourke, within the margin of error of plus or minus 3.5 points.

It’s the first time a poll has shown the El Paso congressman with a lead. Forty-seven percent of respondents favored O’Rourke and 45 percent favored Cruz. Three percent of respondents said they would vote for "other," and 5 percent said they would vote for "none."

On Tuesday, a Quinnipiac poll of likely voters showed Cruz with a 9-point lead over O’Rourke. That poll surveyed likely voters by phone, as opposed to the Reuters and Ispos poll which was conducted online.

A number of factors could lead to the wide variance in poll results, said Nate Silver, editor-in-chief of FiveThirtyEight, a website that focuses on opinion poll analysis, among other things.

"I think Texas is a tough state to poll (lots of new residents, low turnout among certain voting groups, may be hard to reach Spanish-speaking voters) and it’s probably a healthy sign that we’re seeing some disagreement," he tweeted.

The Reuters and Ispos poll also showed Gov. Greg Abbott leading former Dallas County Sheriff and Democratic challenger Lupe Valdez by 9 percentage points — 50 percent for Abbott versus 41 percent for Valdez. The margin in that race is also much closer than in the Quinnipiac poll.