Stocks opened little changed on Tuesday as bullish earnings from blue chips like Ford extended optimism about a strong earnings season, but the debt ceiling stalemate kept investors nervous.

The Dow Jones industrial average <.DJI> was down 24.15 points, or 0.19 percent, at 12,568.65. The Standard & Poor's 500 Index <.SPX> was up 0.22 points, or 0.02 percent, at 1,337.65. The Nasdaq Composite Index <.IXIC> added 5.15 points, or 0.18 percent, at 2,847.95.

The Dow was pressured by weakness in 3M Co , which fell 3.8 percent to $91.45 after its earnings. Ford Motor Co gained 1.3 percent to $13.35.

(Reporting by Ryan Vlastelica)