Donald Trump has backed a $1 trillion dollar plan for infrastructure spending as the campaign enters its final days, one that his advisors claim won't add to the deficit.

Trump's plan would far exceed his Democratic rival's in dollar terms. Hillary Clinton has staked out a plan for $275 billion in additional spending on infrastructure projects over five years, to be paid for with corporate taxes.

Trump has previously said on the campaign trail and in debates that he would double that number. But in recent days, he has said that $1 trillion over a decade would be the goal.

"My contract calls for $1 trillion dollars in infrastructure investment, of which the inner cities will be a major beneficiary," the Republican said Wednesday in Charlotte, N.C.

Most of that funding would come from the private sector, incentivized by government tax credits, Trump's outside economic advisers Peter Navarro and Wilbur Ross told Yahoo News.

The advisers said that the cost of providing tax credits would be offset by the greater economic activity, and thus tax revenues, that would be generated by new projects. They also cited the low interest rate environment as a reason to begin projects now, a point Trump has also made. "If there's ever a great time to do it, it's got to be now," said Ross, a 78 year-old billionaire investor.

More details of Navarro and Ross' plan were not immediately available.

Engineers and business groups favor greater government spending on roads, bridges, ports, and other projects, and have warned that the U.S. currently favors a massive deficit for maintaining old infrastructure and beginning new projects.

Congressional Republicans, however, are skeptical of new spending. Congress passed a major highway spending bill last winter, which House Speaker Paul Ryan has pointed to when asked about infrastructure spending.