Stumping in Detroit, Sen. Rubio talks about Jeb Bush and revamping the tax system

In a speech to the Detroit Economic Club, Republican presidential candidate 
Sen. Marco Rubio said he would overhaul the tax system by cutting the corporate tax rate to 25 percent and increasing the child tax credit to as much as $2,500, among other things.

Rubio, of Florida, pushed several conservative initiatives to improve places across the country like The Motor City, which has been devastated in the past decades by poverty, crime and unemployment.

"I can think of no better place to discuss the challenges and opportunities before our nation than Detroit," Rubio said."No city understands the vision and toil it took to build the American Century better than Detroit."

Rubio's speech was overshadowed, however, by a political brawl in New Hampshire between the two front-runners in the Republican race for the party nomination -- real estate mogul Donald Trump and former Florida Gov. Jeb Bush -- who barbed over immigration and, specifically, birthright citizenship.

Birthright citizenship arose as a debate topic on the 2016 campaign trail after Trump unveiled his controversial plan to change the 14th amendment of the constitution, which allows children of unauthorized immigrants to become U.S. citizens if they are born on American soil.

"I'd much rather find out whether or not ‘anchor babies’ are citizens because a lot of people don't think they are," Trump said to press in New Hampshire Wednesday night.

Bush said: " Mr. Trump doesn’t have a proven conservative record. He was a Democrat longer in the last decade than he was a Republican. The language is pretty vitriolic for sure. But hundreds of millions of dollars to implement his plans is not a conservative plan."

The billionaire candidate also took a shot at Bush during his frenzied press conference just 19 miles away from his rival's town hall.

"I don’t see how he’s electable," Trump said about Bush. "For him to get things done is hard.”

At the Detroit Economic Club Thursday, Rubio was asked if it was difficult to run against Bush, who had been a mentor to the junior senator from Florida when he was a speaker of the state house and Bush was the outgoing governor.

"It's not difficult at all because I'm not running against Jeb Bush. I'm running for president," Rubio said.

Bush included his former mentee in the discussion over birthright citizenship by suggesting that Rubio and Sen. Ted Cruz from Texas, another presidential rival, benefited from birthright citizenship. Rubio flatly discounted that assertion.

" My parents were permanent legal residents of the United States for fifteen years before I was even born.” Rubio told Fox News in an interview in Detroit. "So they're talking about people who were in this country illegally. My parents were never in this country illegally.”

Earlier in the speech, Rubio accused former Secretary of State Hillary Clinton of supporting Democratic policies that increased taxes and government size.

"Hillary Clinton believes the way to win the race for the future is to drive in reverse -- to revert back to more regulations, higher taxes, and bigger government," Rubio stated.