WASHINGTON | With the weak economy driving voter discontent three weeks out from congressional and state elections, President Barack Obama on Monday renewed his call to spend $50 billion on improving the nation’s transportation infrastructure.

His plan calls for rebuilding 150,000 miles of roads — “enough to circle the world six times” — laying and maintaining 4,000 miles of railways, restoring 150 miles of airport runways and advancing a new air-traffic-control system.

Obama said that America’s crumbling infrastructure weakened our economy and left the nation trailing foreign competitors in investment, including China, Russia and Europe. By embarking soon on the infrastructure buildup, he said, “we will create good, middle-class jobs right now.”

Obama’s push comes with the nation’s overall unemployment rate stuck at 9.6 percent. Voters are upset about the economy and job losses, but they’re also unhappy about federal budget deficits and the skyrocketing national debt. The deficit for fiscal 2010, which ended Sept. 30, was $1.3 trillion, the second highest since World War II, according to an estimate last week from the Congressional Budget Office. The highest came the preceding year, $1.4 trillion.

Obama said “this plan will be paid for. It will not add to our deficit over time,” but that depends upon Congress, which hasn’t taken the plan up yet.

Obama spoke upon release of a report by the Treasury Department and Council of Economic Advisers, which concluded that U.S. infrastructure “is not keeping pace” with economic demand and Americans’ expectations and that now would be a “particularly timely and beneficial” time to spend more.

The report said Obama’s plan would create middle class jobs, primarily in construction, manufacturing and retail trade. The report also said that for nine in 10 Americans today, transportation costs eat up nearly 17 cents of every dollar of income.

“Nearly one in five construction workers is still unemployed and needs a job,” Obama said. “And that makes absolutely no sense at a time when there’s so much of America that needs rebuilding.”

With Congress out until mid-November, then back only briefly, there’s no realistic prospect for action on the president’s proposal this year.

Some Republicans are openly hostile and pointed out that Obama’s $814 billion stimulus program, which passed last year, was supposed to improve infrastructure and create jobs but hasn’t done enough.