An official offer from Avis Budget Group Inc. to purchase Dollar Thrifty Automotive Group may still be months away, according to the Wall Street Journal.

An offer for Dollar Thrifty from Hertz Global Holdings is already on the table.

Avis expects the regulatory review process to take several months and believes it is under no immediate pressure to bid for Dollar, according to people familiar with the situation. Dollar shareholders don't have to assess the Hertz bid until a date for a vote is set.

Avis said last month it would make a "substantially higher" offer than the $1.2 billion agreed to between Dollar and Hertz in April. Avis has been examining Dollar's financial statements and has seen nothing to discourage it from making an offer.

Financing for Avis' offer will likely come from Citigroup and Morgan Stanley, people familiar with the matter said. The two banks are also advising Avis on its strategy.

On June 14, the U.S. Federal Trade Commission asked Avis for more information related to its proposed combination with Dollar. Hertz also received a request for more information from the FTC, said a Hertz spokesman.