Iran has made no secret of its hopes for the next round of nuclear negotiations with world powers: Pledges by the West to ease sanctions as a step toward deal making by Tehran.
Iran's pitch is certain to smack head-on into resistance and counter proposals by the West. But it reflects a harder-edged atmosphere before the next talks that suggests envoys will face pressure to stake out at least some tangible bargaining positions, as opposed to the last round where just getting to the negotiating table was considered positive.
Iran has been careful about avoiding ultimatums in a possible sign that it sees the meeting scheduled for later this month in Baghdad as a stepping stone, not a showdown.
No official, for example, has suggested that talks would hit an impasse if the U.S. and European partners balk at immediately rolling back some sanctions, which have targeted Iran's critical oil sector and left the country effectively blackballed from international banking networks.
Instead, Iran has cultivated a sunny approach _ with officials repeatedly saying they are "optimistic" about the May 23 session and their hopes for goodwill gestures from the other side: the five permanent U.N. Security Council members plus Germany.
"We continue to be optimistic about upcoming negotiations," said Iran's Deputy Foreign Minister, Mohammad Mahdi Akhondzadeh, at a conference in Vienna on Wednesday.
From the Western corner, the mood is much tougher.
U.S. officials have rejected the idea that they could ease sanctions against Iran as a confidence-building measure. They have said sanctions will only be pulled back if Iran eases world concern over its nuclear program and complies with demands that include suspending uranium enrichment.
"No one's talking about any sanctions being reversed or canceled at all," said State Department spokesman Mark Toner on April 16, just after the Baghdad meeting was announced.
Two days later, Secretary of State Hillary Rodham Clinton said the question of removing sanctions was "hypothetical."
"We have to see what the Iranians are willing to do, then we have to make sure they do it, and then we have to reciprocate. That's what a negotiation is all about," she told CNN.
Any progress in the talks also further dampens support for possible military strikes on Iran's nuclear facilities.
Israel, which has been the most aggressive in discussing the military option, has been confronted with growing questions over the risks versus rewards of an attack. Some former Israeli security officials, including the ex-chief of internal security Yuval Diskin, have speculated that bombs would only set back Iran's nuclear development by a few years, but could touch off a region-wide war and bring direct retaliation from Tehran proxies such as Hezbollah in Lebanon.
The Obama administration has been trying to convince Israel to give more time for sanctions and negotiations to yield results _ even as Netanyahu branded last month's talks in Istanbul a "freebie" that allowed Iran to continue enriching uranium until the next round.
Istanbul's meeting ended with little more than the plan to meet again. Yet that was portrayed as a success after the swift collapse of negotiations in early 2011.
Iran's uranium enrichment remains the central issue.
Tehran says its enrichment labs are only making nuclear fuel for energy and research reactors, and insists it has no intention of producing weapons. Washington and allies worry the enrichment sites could eventually churn out weapons-grade material.
Now looms the greater challenges of actually hashing out proposals that bridge very different agendas: The West and its allies seeking to rein in Iran's nuclear enrichment, and Tehran strongly refusing to accept any significant reverses in its atomic program.
This is where negotiators may begin to parse the enrichment capabilities.
Iranian officials have indicated they could consider suspending production of 20 percent enriched uranium, which is used for Iran's medical research reactor but is a far higher grade than needed for the country's lone electricity-generating reactor. The 20 percent uranium is a significant concern for the West because it can be converted into weapons-grade material _ at over 90 percent enrichment _ in a matter of months.
Iran also has agreed to answer questions about its alleged attempt to develop nuclear weapons. In the past, Iran refused to even enter into discussions, simply rejecting them as CIA fabrications.
Iranian officials plan to meet May 13-14 in Vienna with experts from the U.N.'s International Atomic Energy Agency. Among the discussions could be efforts to work out guidelines for an IAEA inspection of Iran's Parchin military complex, where the agency suspects secret atomic work has been carried out.
Iranian lawmaker Hossein Nejabat suggested a move by the West to lift some sanctions could bring an Iranian pledge not to exceed 5 percent enriched uranium. But Iranian officials _ as high as Supreme Leader Ayatollah Ali Khamenei _ flatly reject any calls to halt uranium enrichment entirely.
"Lifting sanctions is our least expectation," added hardline parliament member Gholam Ali Haddad Adel.
It appears unlikely that U.S. or European governments would offer any rollback in sanctions without considerable concessions from Iran in return.
State Department spokeswoman Victoria Nuland said Monday that Washington wants "to see Iran live up to its international obligations including the suspension of uranium enrichment as required by multiple UN Security Council resolutions."
A full boycott of Iranian oil goes into effect July 1 across the European Union, which once accounted for about 18 percent of Iran's crude exports. Iran threatened to block Gulf tankers in retaliation for tougher sanctions, at one point shooting oil prices above $120 a barrel.
A prominent Iranian political analyst, Sadeq Zibakalam, said sanctions may become the linchpin on whether talks stall in Baghdad or move forward.
"Sanctions have harmed Iran. They also harmed Europeans," he said. "Sanctions also have caused a hike in the oil price, worsening the global economic downturn ... Neither Iran nor the West benefit."
Murphy reported from Dubai, United Arab Emirates. Associated Press writer George Jahn in Vienna and Bradley Klapper in Washington contributed to this report.