Meanwhile, the Bharatiya Janata Party mounted pressure by moving the Election Commission and seeking action against him and his wife for "hiding facts" about their income.
Rushing to the capital, Singh presented his version of the issue to Congress General Secretary Ambika Soni, who is in-charge of the state.
The BJP had alleged that Singh had taken a "bribe" from a private power company to grant an extension to its project.
The chief minister, however, could not meet party chief Sonia Gandhi or Rahul Gandhi.
Singh had flown to the national capital on Tuesday to explain his position to the party high command.
During the meeting with Soni, he is understood to have stated that it was a malicious campaign by the BJP.
The charges against him have come at a time when the Congress is seeking to take a high moral ground on the issue of corruption.
On its part, BJP stepped up its attack on Singh on the issue and demanded his resignation. It accused Singh and his wife Pratibha Singh, a Member of Parliament, of "hiding facts about their incomes in affidavits filed during polls".
Party MP and Bharatiya Janata Yuva Morcha chief Anurag Thakur met Chief Election Commissioner V S Sampath and handed over a memorandum demanding action against Singh and his wife.
"Virbhadra Singh should resign immediately. Let the Congress decide on any other candidate for chief ministership. This is the fifth corruption charge against Singh. This is also a test for the Congress to act against him to prove if it is really serious on the issue of corruption. This will also prove the leadership of Rahul Gandhi -- whether he means what he has been saying on corruption or if it is only double-speak," Thakur said.
Pratibha Singh, who is the Congress MP from Mandi, is also facing allegations of corruption.
She had met a number of senior party leaders at the All India Congress Committee headquarters on Tuesday to explain her position on the issue.
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