President Donald Trump, in his State of the Union speech Tuesday, plans to discuss a $1.5 trillion infrastructure improvement plan, White House economic advisor Gary Cohn told CNBC.

Fresh off a victory on a tax reform plan that Congress approved in December, the president next wants to focus on rebuilding the nation’s aging system of highways, transportation and other public works facilities.

In an interview on “Squawk Box,” Cohn called infrastructure “the next leg of the stool in our economic agenda.”

“He’s going to talk about a trillion and a half dollars of investment, but more importantly, he’s going to talk about streamlining the approval process on infrastructure,” Cohn said. “Right now, we have an infrastructure approval process that takes seven to 10 years to build relatively simple roads. We need to streamline that to less than two years.”

Cohn added that Trump might even suggest getting the process down to less than one year.

Trump thus far has overseen a sharp uptick in economic activity, with GDP growth expected to be around 3 percent for the second year of his term. Other areas, though, particularly wage growth and productivity, remain weak.

Adopting an aggressive infrastructure program would help bring up some of the lagging parts of the economy, Cohn said.

“I think we all know how important infrastructure is to this country and how it is holding back economic growth and it’s holding back productivity,” he said. “When you look at some of the economic data, the one number that people pick on is productivity. We need more productivity growth. Our infrastructure and building our infrastructure and rebuilding our infrastructure can clearly lead to productivity growth in this country.”

Cohn, the former chief operating officer of Goldman Sachs, is director of the National Economic Council.