Jeb Bush

George P. Bush, the Texas land commissioner, is breaking with his father, a former Donald Trump Republican primary rival, to back the GOP nominee. George P. Bush's move comes after a nasty Republican primary battle in which Trump repeatedly mocked Jeb Bush, a former Florida governor, as "low energy," among other insults.

The former Florida governor repeatedly took the fight to front-runner Donald Trump in Las Vegas Tuesday night as the Republican Party's 2016 class met on the debate stage for the last time this year.

It's a risky strategy for the former Florida governor, still considered the GOP front-runner by many party officials, but a move his advisers suggest is necessary to reverse Trump's unlikely ascension to the top of the 2016 presidential class.

The former Florida governor told reporters Trump should read his book, "Immigration Wars," if he wants to learn how to deal with illegal immigration. Earlier, he met privately with local, state and federal officials in this city along the Rio Grande across from Reynosa, Mexico.

Trump has proposed building a massive border fence and kicking out the estimated 11 million people who are in the U.S. illegally before allowing the "good ones" and "talented" ones back in.

Bush reported more than $1.8 million in speaking fees since the beginning of 2014. That's an average of just over $42,000 for each speech.

His single largest source of income was Jeb Bush & Associates, which collected his speaking fees and performs strategy and consulting work. Bush says he no longer owns it.

The former Florida governor was in the central part of the state earlier this week, speaking to a diverse group of 150 pastors and other religious leaders, repeating his oft-stated pledge to campaign in "every nook and cranny" of the country. 

On Friday, he'll be one of only two Republican presidential candidates to address the National Urban League's annual conference, joining Hillary Rodham Clinton and two other Democrats seeking the White House.