New Delhi: Even as the Left yesterday formally withdrew support for the ruling coalition, top constitution experts said the president need not necessarily ask the government to prove its majority in parliament, but any party or MP can bring the vote of no-confidence.

"The president can well decide that there is no need for a confidence vote, specially after the Samajwadi Party, with 39 MPs, has already pledged its support. But it will be open to the president to ask the opposition to move a vote of no-confidence," K.K. Venugopal, a top constitutional expert said.

"The Samajwadi Party has already pledged support. She [President Pratibha Patil] need not make an exact count of MPs supporting the government. If she is satisfied that the government has the support of a majority in the house, she need not necessarily ask the government to move a confidence motion," Venugopal said.

Shanti Bhushan, a former law minister and senior Supreme Court advocate agrees: "According to the constitution, the president is not even required to make up her mind on how many MPs are supporting the government."

President Patil can tell the Left parties or any MP who thinks the government has lost confidence of the house that if they think so it's up to them to bring a no-trust vote in the house, Bhushan said.

"The rules of parliament provide for a solution in such a scenario. If any individual MP or party wants to bring a no-trust vote, they are free to so within established parliamentary procedures.

The Manmohan Singh government has said categorically that it will go ahead with the International Atomic Energy Agency (IAEA) safeguards agreement only after the trust vote, signalling that it was ready to face this.

According to reliable sources, the government is planning to convene a special session of parliament July 21-22 to face a trust vote as it wants to submit the safeguards pact for ratification to the IAEA board when it meets in Vienna July 28.