Congress party President Sonia Gandhi has refused to become the next prime minister.

Confirming this, a senior Congress official told rediff.com, "There is a gadbad (problem). Sonia Gandhi is refusing to become the prime minister. She wants to back out."

What about a change of heart at a later stage? "Woh maan nahin rahi hai (she is not willing to listen)," the Congress leader said.

According to highly reliable sources in the Congress, she has told her top leaders in unambiguous term that she will not head the new government.

Unless Congress leaders and the party's allies persuade her to accept the PM's post, the Congress' choice for prime minister will be announced later this evening.

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The front-runners are two former finance ministers -- Pranab Mukherjee and Manmohan Singh.

The option of a non-Congress leader is not under consideration, a party source said.

The source said she has been reluctant to don the mantle since the election results were announced, and had spent a considerable amount of time consulting a cross-section of opinion. Obviously, she does not want to weaken the new government over the opposition to her foreign origin.

Sonia Gandhi had intended to read out a letter refusing to accept the nation's highest executive office at the Congress Parliamentary Party meeting on May 15.