NEW YORK (AP) — U.S. stock futures are falling ahead of a vote in the Senate to raise the nation's borrowing limit.

The Treasury Department has said that Congress must raise the debt ceiling by the end of Tuesday in order to allow the government to pay all of its bills. The Senate is expected to vote on the bill before the market closes. The House passed the measure Monday night.

Investors are growing concerned about the U.S. economy and will be looking at consumer spending figures that are expected to be released before the market opens.

Ahead of the opening bell, Dow Jones industrial average futures are down 41 points, or 0.3 percent, to 11,999. S&P 500 futures are down 6, or 0.4 percent, to 1,274. Nasdaq 100 futures are down 9, or 0.4 percent, to 2,337.