Treasury Secretary Henry M. Paulson Jr. on Tuesday left open the possibility that the Bush administration could tap the second half of the $700 billion bailout fund, although he said he had no immediate plans to do so.

After the latest commitment of $20 billion to buttress moves by the Federal Reserve to get credit flowing to businesses and consumers, Paulson said, “We have no timeline for going to Congress. ... If and when that comes, we’ll describe the programs we have and the challenges before us.”

For now, Treasury and the Federal Reserve Bank of New York — which is headed by Paulson’s designated successor, Timothy F. Geithner — are moving to unfreeze consumer credit markets.

The New York Fed announced that it will extend up to $200 billion in loans to holders of securities backed by consumer and small- business loans. It will also buy up to $100 billion in direct debt obligations of Fannie Mae, Freddie Mac and the Federal Home Loan banks, and up to $500 billion in mortgage-backed securities guaranteed by Fannie, Freddie and Ginnie Mae.

Under the bailout law enacted Oct. 3, Congress could block the release of the second $350 billion of the $700 billion Troubled Asset Relief Program if lawmakers enact a joint resolution of disapproval. Several conservative House Republicans have already introduced just such a disapproval resolution, which would be considered under special fast-track rules in the House should Paulson request release of the second half of the funding.

The Treasury Department has allocated all but $20 billion of the first $350 billion. Paulson had planned to leave the second $350 billion untouched in deference to the incoming Obama administration, but left the door open to tapping that second installment. “We’re focused on the programs.  . . .  When the time is right we will avail ourselves of that congressional process,” Paulson said.