Former chief election commissioner T S Krishnamurthy on Tuesday said the 'one nation one election' idea is very attractive but cannot be put into practice without a Constitutional amendment providing for fixed tenure for legislatures.

Prime Minister Narendra Modi has invited heads of all political parties which have at least one MP either in the Lok Sabha or Rajya Sabha for a meeting Wednesday to discuss the "one nation, one election" and some other important matters.

Krishnamurthy, who oversaw the 2004 Lok Sabha elections, said a lot of administrative arrangements, including increasing the strength of paramilitary forces for poll duties, might be required for holding simultaneous elections but they are possible.

The idea has several advantages, he said, but the biggest impediment in its implementation is constitutional provision relating to no-confidence motion and related issues.

"The only way out is amendment by which you say...a vote of confidence will be effective only if some other person is elected as a leader; otherwise old government will continue. Unless you provide for fixed tenure of the House, it's not possible", he told PTI.

"...transitional provisions may be required because some Houses would have had two-and-half years (of its tenure), some would have had four-and-half years, like that. Transitional provision providing for extending the (tenure of) Houses to a common date may be required," Krishnamurthy said.

He further said it's very difficult to guess if a consensus would emerge among political parties on the issue.