Mitt Romney kept his focus on the national debt Wednesday morning, blasting President Obama for increased government debt.

Standing in front of a digital sign showing an ever-increasing federal deficit, Romney warned that if the United States doesn't get the debt under control, "they're going to be dramatically raising taxes over time" to pay for it.

"It's high time that we have a president who will stop this spending and borrowing inferno," he said to applause from the senior-heavy crowd in St. Petersburg, Fla.

Romney's campaign pivoted back to the national debt this week with a major speech in Iowa on Tuesday. He rehashed much of that speech Wednesday in Florida, a must-win state for Romney that has one of the highest foreclosure and unemployment rates in the country, seeking to tie it to a larger narrative about the jobs and the economy.

President George W. Bush endorsed Romney on Tuesday, but Romney didn't return the favor, criticizing both sides for ratcheting up the debt.

"[President Obama] was very critical of his predecessor for the debts his party put in place. It sure is true that you can't blame one party or the other," he said, agreeing with Obama that the $4 trillion increase in the national debt under Bush wasn't good before lambasting him for increasing the debt at a much faster pace.

"This president hasn't stopped that, he's added to it. Every year, every day it's getting bigger and bigger," he said. "This is where your taxes are going. They're going to pay for the interest on the hidden debt.

"My generation and those on this stage by and large are not going to be paying off the $520,000," Romney continued, referring to the older voters gathered around him. "We won't pay it off. You guys will."

Romney isn't as well-known as Obama — nearly one-third of voters didn't have an opinion of him in a recent national poll — and both sides have sought to define him in recent days, with the Obama campaign attacking Romney's time as head of Bain Capital and Romney pushing back with his own ads. He acknowledged in the speech how important it was to define himself in the coming days.

"There are a lot of people who haven't heard from us," he said before imploring those in the audience to spread the word to younger voters and recent Florida transplants.

The former Massachusetts governor promised to increase oil production, arguing that more drilling would lead to a "manufacturing rebirth in this country that will help put people back to work and good jobs."

He also called for increased military spending, a stance seemingly at odds with his calls to reduce the deficit, and promised to repeal Obama's health insurance reforms, a strong applause line at every Republican event.