(CNN) – Democratic presidential candidates Hillary Clinton and Barack Obama are in a tight race in Texas, according to a “poll of polls” calculated by CNN on Thursday.
An average of three polls of likely Democratic voters has Sen. Barack Obama at 48 percent and Sen. Hillary Clinton at 45 percent. Seven percent were unsure.
The average also shows Sen. John McCain, the presumptive GOP nominee, holding a nearly 20-point lead over former Arkansas Gov. Mike Huckabee among likely Republican primary voters. McCain has 53 percent to Huckabee's 34 percent, and Texas Rep. Ron Paul has 9 percent. Four percent were unsure.
Texas voters will be joined by those in Ohio, Vermont and Rhode Island when they head to the polls on March 4. With Obama surging into the lead on 11 straight wins since Super Tuesday, Clinton's supporters admit that she must do well in Texas and Ohio if she is continue to battle for the nomination.
CNN's Texas poll of polls results were calculated using three surveys: a Belo/Public Strategies poll conducted February 24-25, an American Research Group poll conducted February 23-24, and a CNN/Opinion Research Corporation poll conducted February 22-24.
Earlier, an American Research Group poll of likely Democratic voters on February 13-14 showed Obama ahead, 48-42, with 10 percent undecided. A CNN poll taken between February 14-17 showed Clinton ahead, 50-48.
–CNN.com Senior Political Producer Scott Anderson