Phoenix ? Struggling to pacify his party’s warring wings, President Bush is moving toward allowing illegal immigrants who came to the U.S. before February 2004 to qualify for guest-worker visas. People smuggled in after then would be deported.

State leaders in Arizona and New Mexico have stepped up pressure on the Bush administration and the Republican-led Congress to better police U.S. borders and deal with an estimated 10 million people who are living illegally in this country.

“They’re trying to split the baby,” Sen. John McCain, R-Ariz., said of the White House plan, “and I don’t think they can do that.”

Bush and his advisers are caught between their supporters in the business sector, who believe the economy needs those workers, and conservatives whose priority is to clamp down on illegal immigration. The White House hopes to have a detailed proposal to Congress in late September or early October.

McCain, who ran against Bush for the 2000 GOP nomination and may seek the White House in 2008, is sponsoring a bill with Sen. Edward M. Kennedy, D-Mass., that would create 400,000 three-year visas for guest workers. The legislation has the flexibility to add more in the future and would let undocumented workers stay in the U.S. while they apply.

A competing plan by Sen. Jon Kyl, R-Ariz., would create two-year visas and require that guest workers and illegal immigrants leave the U.S. before they can apply for the chance to work legally in the country.

Conservative House Republicans tend to favor Kyl’s tougher approach. McCain mocks it.

“Turn yourself in so we can send you back to Mexico,” said McCain, throwing his head back in laughter during an interview at his Arizona office last week. “It’s not going to happen.”

The White House seems to agree with McCain.

According to administration and congressional officials who took part in a series of White House meetings this summer, Bush does not favor requiring illegal immigrants to be sent home to apply for the visas.

In a nod to his conservative base, however, the president has rejected a part of the McCain-Kennedy bill that the White House believes would put illegal immigrants on an automatic track to citizenship, the officials said.