Lawmakers pressed President Bush on Sunday to spell out the cost to Americans of the occupation of Iraq, which a leading Republican said would top $30 billion over five years for operations alone.

Sen. Richard Lugar, an Indiana Republican and chairman of the US Senate Foreign Relations Committee, said the $30 billion was in addition to military costs that have been running about $4 billion a month.

"That's the target," Lugar told "Fox News Sunday." "That's about what the budget was... during the Saddam days, just to run the country."

Sen. John McCain, an Arizona Republican and member of the Senate Armed Services Committee, wrote in The Washington Post that the administration had to be explicit about what is going to be required.

"America's mission in Iraq is too important to fail. Given the stakes, we cannot launch this 'generational commitment' to changing the Middle East on the cheap," McCain wrote in an editorial.

"The administration should level with the American people about the cost and commitment required to transform Iraq."

The demands on Bush intensified as he returned to Washington from a month-long stay at his Texas ranch. The vacation was marred by violence in Iraq including Friday's car bombing in Najaf, which killed a top Shiite Muslim leader, and the bombing of the UN headquarters in Baghdad.

Administration officials have said Bush may ask the US Congress to provide $2 billion to $3 billion over the short term for Iraq and some congressional sources are expecting a push for an emergency spending bill of $20 billion or more this year.

Congress passed a $60 billion emergency spending bill in April for US operations in Iraq and Afghanistan.

The US civil administrator in Iraq, Paul Bremer, said last week he needed tens of billions of dollars for the next year alone, citing $16 billion to deal with water problems and $13 billion for electrical power.