WASHINGTON  Over the years, several presidents have been forced to ponder the delicate (and sometimes unpleasant) question of whether to move the in-laws into the White House.

Ulysses S. Grant shared space with his father-in-law, who grumbled and squabbled with other relatives, historians say. Harry S. Truman lived with his mother-in-law, who declared that she knew “dozens of men better qualified” to preside over the Oval Office.

On Friday, the transition team of President-elect Barack Obama confirmed that his 71-year-old mother-in-law would be moving, at least temporarily, into the grand residence at 1600 Pennsylvania Ave. While Grant and Truman might have been forgiven for gritting their teeth at such a prospect, Mr. Obama has said he will be delighted to have his wife’s mother, Marian Robinson, join the first family in Washington.

After all, Mrs. Robinson, known as a loving, tough-minded matriarch who rarely shies from speaking her mind, has been the bedrock of the Obama family. During the presidential campaign, she retired from her job as a bank secretary to care for the Obama girls, Malia, 10, and Sasha, 7, while their parents were on the road.