Bharatiya Janata Party (BJP) leader LK Advani on Friday asked Prime Minister Manmohan Singh to replace Pratibha Patil as the ruling United Progressive Alliance (UPA) presidential candidate with a "more suitable person."
In a statement, Advani said serious charges of wrongdoing have been levelled against her and she was "a person unfit to occupy the highest constitutional office."
The nominations for the presidential election close on Saturday.
Advani's appeal came within hours of the opposition National Democratic Alliance (NDA) filing a complaint with the Election Commission accusing the Congress of using "pressure tactics" to get support for Pratibha Patil for the July 19 election.
The BJP leader asserted that the allegations against Patil being involved in a cooperative bank wrongdoing and the charges by a woman of involvement of Pratibha Patil's brother in a murder were "not cooked up."
He said it was a serious revelation that tars the reputation of any person in public life whose norms of probity demand that he or she comes clean.
"Each of these taken together, the revelations are of such grave nature that they completely and incontestably render a person unfit to occupy the highest constitutional office in the country," Advani said.
"I appeal to you (Prime Minister), therefore, to once again consult your ministerial colleagues and leaders of the allies of your party and nominate any other suitable person for the presidential election," he said in the statement.
Advani said he was sad the prime minister had defended Patil and accused the opposition of mudslinging.
He said the "revelations" could be sourced to "verifiable records of the Reserve Bank of India (RBI), other government agencies and memorandum submitted by the people affected by the scandals".
Advani said the ruling coalition should choose somebody else in place of Patil before July 4, which is the last date for withdrawal of nominations.
The NDA alleged that the Congress' petition for disqualification of former external affairs minister Natwar Singh as Rajya Sabha member showed that it was using pressure to secure support for Patil because Singh was one of the proposers for Vice-President Bhairon Singh Shekhawat's candidature.
NDA spokesperson Sushma Swaraj, who led a delegation to the Election Commission, told reporters that the Congress claim that it was its second petition for Singh's disqualification as Rajya Sabha member was "false".
Brushing aside the Congress' claim that it had filed a similar petition in May, Swaraj said that no such petition had been filed with the Rajya Sabha Secretariat.
Meanwhile, ten more nominations for the presidential election were filed with the Secretary General of the Lok Sabha who is the Returning Officer and of these five have been rejected.