WASHINGTON (Reuters) -- President Bush said Monday the investigation into the outing of a covert CIA operative was "very serious," even as Republican allies started casting aspersions on the prosecutor and the possibility of perjury charges.The mixed signals came as special prosecutor Patrick Fitzgerald appeared close to indicting top White House officials in the nearly two-year investigation, lawyers involved in the case said.Fitzgerald's investigation has focused largely on Karl Rove, Bush's top political adviser, and Lewis Libby, Vice President Dick Cheney's chief of staff, and their conversations with reporters about CIA operative Valerie Plame in June and July of 2003.After a Cabinet meeting, Bush was asked whether he agreed with Republican suggestions that Fitzgerald may be overzealous and that possible perjury charges would be little more than legal technicalities."This is a very serious investigation," Bush said. Rove sat behind the president in the Cabinet room; across the room sat Libby.Lawyers involved in the case say Fitzgerald has laid the groundwork for indictments this week, and that he was focusing on whether Rove, Libby and others may have tried to conceal their involvement in the leak from investigators.Indictments against any top officials would be a severe blow to an administration already at a low point in public opinion, and would put a spotlight on aggressive tactics used by the White House to counter critics of its Iraq policy.Plame's identity was leaked to the media after her diplomat husband, Joseph Wilson, challenged the Bush administration's prewar intelligence on Iraq.Lawyers said one possibility was a "split decision" in which Libby is indicted and Rove is spared.But one lawyer involved in the case said that could be just as damaging to the White House because of the possibility that Cheney himself could be implicated in any resulting trial."It's improbable to think of Libby out there as a free agent," the lawyer said.Bracing for bad news, White House officials are discussing how to cope without Rove and Libby if they are indicted and forced to step down.Asked about the uncertainty, White House press secretary Scott McClellan said, "We've got to keep our energies focused on the things we can do something about."While Fitzgerald could still charge administration officials with knowingly revealing Plame's identity, the lawyers said he appeared more likely to seek charges for easier-to-prove crimes such as making false statements, obstruction of justice and disclosing classified information.Over the weekend, Republicans launched a pre-emptive strike against possible charges for perjury.Sen. Kay Bailey Hutchison of Texas derided any potential perjury charge as a "technicality," and suggested Fitzgerald may be trying to show that "two years' of investigation was not a waste of time and dollars."Other Republicans with close ties to the White House suggested that Fitzgerald was looking at perjury and obstruction charges because he was having trouble proving that officials knowingly leaked the identity of a covert operative.In contrast, Bush has publicly praised Fitzgerald's investigation, saying earlier this month that "he's doing it in a very dignified way."Copyright 2005 Reuters. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.