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MIAMI (CBSMiami) – Donald Trump has made a big jump in the latest Monmouth University Poll of Republican voters nationwide and is now nipping at the heels of frontrunner Jeb Bush.

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When Republicans are asked who they would support for the GOP nomination for president, Jeb Bush nominally leads the pack with 15%, followed by Donald Trump at 13%, and Ted Cruz at 9%.

The next group of candidates includes Scott Walker (7%), Mike Huckabee (7%), Marco Rubio (6%), Ben Carson (6%), and Rand Paul (6%). The rest of the field garnered 2% or less of the vote.

Four of the candidates have entered the race since the last Monmouth poll was taken in June. Of these, Jeb Bush’s support increased 6 points from 9% and Donald Trump’s support increased 11 points from 2%. Bobby Jindal’s support remains unchanged from 1% and Chris Christie’s support has dropped two
points from 4%.

“The biggest poll bump over the past few weeks has been for Donald Trump. But you’ve got to wonder if his support has already plateaued since many Republican voters don’t view him as a serious candidate,” said Patrick Murray, director of the Monmouth University Polling Institute in New Jersey.

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The poll asked GOP voters whether any of the Republican candidates in the presidential race are doing it more to get themselves publicity than to make a serious run for the office. While one third (32%) said no and 1-in-5 (21%) were unsure, nearly 4-in-10 (39%) named Donald Trump as a candidate who is in it more for the publicity.

Jeb Bush now garners a solid 50% favorable to 30% unfavorable rating among his party’s electorate. This marks an improvement over his narrowly positive 40% to 35% rating in June.

Trump’s voter rating has gone from a decidedly negative 20% favorable and 55% unfavorable in June to just a narrowly negative 40% favorable and 41% unfavorable rating now. He has also made an incredible surge among the Tea Party supporters – flipping his decidedly net negative 20% to 55% rating with this group to a decidedly positive 56% favorable to 26% unfavorable rating now.

“It looks like Tea Party voters are really responding to Trump’s aggressive illegal immigrant message,” said Murray.

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The Monmouth University Poll was conducted from July 9 to 12, 2015 with 1,001 adults in the United States. This release is based on a sample of 336 registered voters who identify themselves as Republicans or lean toward the Republican Party. This voter sample has a margin of error of 5.4 percent.