GOP budget hawk to Trump: I'm worried about the $20 trillion national debt

Sen. Portman: Can't get balance budget without focusing on all sides

A day after President Donald Trump's address to Congress, Republican Sen. Rob Portman told CNBC he's concerned about the budget.

While applauding the tone and the conservative agenda from Trump during Tuesday night's speech, Portman cautioned about adding to the nearly $20 trillion national debt.

"We've got to be sure we do keep our focus on our fiscal house," the Ohio Republican said on "Squawk Box."

Trump, in his first address to a joint session of Congress, said the federal debt doubled under former President Barack Obama.

Portman, director of the Office of Management and Budget under President George W. Bush, said he'd like to see policies that address ballooning debt projections.

He said Trump needs to look at increasing military spending in the context of the overall budget, such as cutting elsewhere and growing the economy to help pay for it.

In addition to advocating for more money to build up the military, Trump on Tuesday night called for $1 trillion for upgrading the nation's infrastructure systems.

Portman, who also served as Bush 43's U.S. trade representative, agrees with Trump that the U.S. needs "both fair and free trade."

"But we have to be careful on the protectionism side," added Portman who had been discussed during the campaign as a possible vice presidential pick for Trump.