WASHINGTON (Reuters) - The Senate gave final congressional approval on Tuesday to a nearly $1 trillion farm bill that trims food stamps for the poor, expands federal crop insurance and ends direct payments to farmers, and sent it to President Barack Obama for his expected signature.

The Senate voted 68-32 to pass the sweeping bill, which is more than a year overdue after congressional negotiations bogged down on a host of issues, including the size of cuts to the food stamp program.

Last week the House of Representatives passed the legislation by a wide margin. The White House has said Obama would sign the bill.

The Congressional Budget Office says the $956 billion legislation will save $16.6 billion over 10 years compared to current funding. Using a different scoring, congressional leaders put the savings at $23 billion.

About $8 billion in savings over 10 years comes from cuts to the Supplemental Nutrition Assistance Program, commonly known as food stamps, which accounts for nearly 80 percent of the bill's spending. The program provides funds to about 47 million low-income people to buy food.

The food stamp cut was well below the $40 billion reduction advocated by the Republican-led House, but still double the amount originally supported by the Democratic-run Senate.

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