President Bush said Tuesday that Iran's initial response to a package of incentives and threats on the nuclear impasse "sounds like a positive step to me."

President Bush, right, Texas Gov. Rick Perry, and Commissioner of Customs at the Bureau of Customs and Border Protection W. Ralph Basham, left, visit the Laredo Border Patrol Sector Headquarters in Laredo, Texas, Tuesday, June 6, 2006. [AP]

"We will see if the Iranians take our offer seriously," Bush said in Laredo, Texas, where he was speaking about immigration overhaul. "The choice is theirs to make.

"I have said the United States will come and sit down at the table with them so long as they are willing to suspend their enrichment in a verifiable way," Bush said. "So it sounds like a positive response to me."

European Union foreign policy chief Javier Solana laid out the potential rewards and consequences Tuesday during a visit to Tehran. He later told Secretary of State Condoleezza Rice by phone that the Iranians had said they would need time to consider the proposal, State Department spokesman Sean McCormack said.

Solana called the discussions "very useful and constructive," McCormack said.

Bush said in Laredo that he wanted to resolve the issue with Iran diplomatically.

Earlier in the day, the administration said it would give Iran "a little bit of space" to consider the package but added that the offer was not open-ended.

"It's a matter of weeks, not months," McCormack said, echoing the vague deadline set out by Secretary of State Condoleezza Rice before the package was presented to Tehran.

U.S. officials would not discuss specifics, saying that Iran needed time to review the package and ask questions in private.

"We want to give this every opportunity to succeed," McCormack said. "The diplomacy, I would say, is at a sensitive stage."

The package includes a promise of Western technical help in developing peaceful civilian nuclear energy if Iran stops enriching uranium, a waiver of U.S. legal restrictions to allow export of some agricultural technology, access to U.S. aircraft parts or new Boeing Co. planes to upgrade Iran's aging fleet and U.S. and European backing for Iran to join the World Trade Organization, diplomats and others said.

The proposal was agreed on last week by the United States, Britain, France, China and Russia ¡ª the five veto-wielding members of the U.N. Security Council, plus Germany. Those nations would be expected to move for Security Council sanctions such as travel and financial restrictions on Iranian officials if Tehran does not take the deal or if negotiations fall apart.

Top Iranian nuclear negotiator Ali Larijani said the initiative contains "positive steps" but also some "ambiguities."

"There are robust measures on both sides, both the incentive side as well as the disincentive side," McCormack said. "It presents the Iranian government with a very clear choice on both sides of the road."

The United States reversed course last week and offered to bargain directly with the Iranians if they first put disputed nuclear development on hold. The Bush administration accuses Iran of bankrolling terrorism and criticizes anti-Semitic statements by its leader.

Although some in the administration worry about conferring legitimacy on Iran's leaders by talking face to face, Rice decided about six weeks ago that only direct U.S. involvement could revive European-led talks that stalled last year.

The package presented to Tehran on Tuesday would be on the table for any new talks involving the United States.