As nuclear talks between Iran and the P5+1 (the five permanent UN Security Council members, plus Germany) continue, both sides have offered hope that they’ll reach a comprehensive agreement. The International Atomic Energy Agency (IAEA) and Wendy Sherman, Under-Secretary of State for Political Affairs who heads the U.S. delegation have both admitted that Iran has kept its promises under the Geneva Accord, signed between the two sides last November. The U.S. and its allies have also delivered on their part of the deal, hence providing Iran with slight, but still significant, relief from the crippling sanctions that they have imposed on Iran.

U.S. officials have expressed optimism that the final and comprehensive agreement will end the dispute over Iran’s nuclear program. The Iranians, and in particular Foreign Minister Javad Zarif and President Hassan Rouhani, have been saying the same for quite some time. But, of course, drafting the text of the agreement is one thing, the demand by P5+1 that Iran must drastically cut back on the scope of its nuclear program and whether Iran agrees, are completely difficult, and potentially deal-breaking issues. It is here that the role of Iran’s supreme leader, Ayatollah Ali Khamenei, is paramount.

The fact is Mr. Khamenei is trapped between a rock—the Iranian nation—and a hard place—his hardline supporters. The Iranian people elected President Rouhani in a landslide last June, and have been demanding uprooting of the vast corruption under Mr. Rouhani’s predecessor, Mahmoud Ahmadinejad, a functioning and robust economy, better relations with the West, and a more open and tolerant political system that puts Iran on a firm and definitive path toward a true and inclusive democracy. Resolving the nuclear dispute with the West and lifting of the sanctions represent major steps in this direction. Mr. Khamenei has supported the nuclear negotiations. As far back as 21 March 2013, he signaled a fundamental change in his position regarding nuclear negotiations with P5+1, and has consistently said that he supports the negotiations as long as Iran’s nuclear rights are recognized and respected. In a speech on April 9, Mr. Khamenei emphasized again his support for the nuclear negotiations, although he also accused the U.S. of presenting an image of Iran’s nuclear program and goals that are far from reality.

But, the hard place—Iran’s hardliners that represent Khamenei’s main social base of support—is not interested in a nuclear compromise. The hardliners have been using every opportunity and excuse to attack the Rouhani administration, have likened the nuclear deal to the Holocaust, have claimed that Iran has made too many concessions for too little in return, and have used the Majles [the Iranian parliament] to create problems for the government by constantly summoning various ministers, and in particular Mr. Zarif, to explain his position. They have even threatened to impeach him.

Mr. Khamenei has also made statements that the hardliners, both in Tehran and Washington, point to as indications that he is not interested in a reasonable compromise. For example, between the signing of the Geneva Accord and the beginning of the new round of negotiations in Vienna in February, Mr. Khamenei expressed his lack of hope for the negotiations to succeed. In particular, he said on February 17 that although he supports the nuclear negotiations, he does not believe that the negotiations with the U.S. “will go anywhere.” The mainstream media in the U.S., the hawks and the Israel lobby that are looking for any excuse to scuttle the diplomatic process, quickly interpreted Khamenei’s speech as indicating his unwillingness to compromise. But, as explained elsewhere, Mr. Khamenei was misquoted: he supports the negotiations and is definitively interested in a diplomatic solution, but he is pessimistic about the prospects for better, nonhostile relations with the United States.

Likewise, Tehran’s hardliners, and in particular some of the leading commanders of the Islamic Revolutionary Guard Corps [IRGC] and intelligence officials in the Ahmadinejad administration, have also used Mr. Khamenei’s pronouncements to justify their opposition to the nuclear negotiations. The opposition became louder after the European parliament approved a resolution in which it criticized Iran for its human-rights record and proposed to open an office in Tehran by the end of this year, presumably to enable the European Union to monitor the state of human rights in Iran. One member of the Majles, Nader Ghazipoor, declared that “the Iranian nation will not accept the disgrace of having another ‘den of spies’ on its ‘sacred soil’,” a reference to the old U.S. embassy in Tehran. Other hardline MPs suggested that the resolution will negatively impact the negotiations and have even suggested withdrawing from them. There is also another suggestion in the Majles to fingerprint members of European delegations that travel to Iran, presumably to “humiliate” them.

The fact is, nuclear negotiations with Iran would not have advanced as far as they have if the Rouhani administration did not have Mr. Khamenei’s support. Therefore, the question is why Mr. Khamenei makes statements that might be interpreted as indicating his unwillingness to compromise. The answer, as already pointed out, is that he is trapped between rock and a hard place, and that the reasons for his statements that “please” the hardliners are twofold.

One reason is, of course, that the hardliners, the most important base of support for Mr. Khamenei, oppose the negotiations. Some of the hardliners do so for ideological reasons. They do not trust the United States, and are afraid that President Rouhani and Mr. Zarif will make too many concessions in order to close Iran’s nuclear dossier. Others oppose the negotiations because during the Ahmadinejad administration they gained their political and economic power as a result of the hostility of the U.S. toward Iran, and are afraid that if the negotiations succeed and the relations between the two nations improve, they will lose everything. Thus, in order to control such hardliners, Mr. Khamenei must appear resolute at home.

The second reason is that Mr. Khamenei is trying to create a political cover for himself and his authority, in case the negotiations fail. He recognizes that he does not have the authority that Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic, enjoyed with the people. When he declared to the nation in 1988 that he would end the war with Iraq, he also took full responsibility for it, after opposing it for six years after Iran’s military had beaten back the Iraqi army and expelled it from Iran’s territory. Mr. Khamenei is maneuvering to put himself in a position to be able to declare that he knew all along that the U.S. is not interested in a diplomatic resolution to the conflict, if the negotiations fail, and that the failure is not his fault. Thus, his pessimism about reaching an agreement with the U.S. is mostly for his hardline supporters, as well a way of securing his own authority.

But, despite the fact that the hardliners are the most important base of support for Mr. Khamenei, he also recognizes that they have been cornered by the track record of Ahmadinejad that he himself had helped bring to power and had strongly supported for at least six years. Hardly a day goes by without the discovery of another major Ahmadinejad-era corruption case. In addition, Iran’s economy suffered greatly during Ahmadinejad’s second term. In particular, it contracted by about 5.7 percent in 2012, and by 1.7 percent during most of 2013. These, together with the extreme political repression that the hardliners imposed on the nation as a result of the Green Movement of 2009-2010, created an explosive situation, but also completely discredited the hardliners. Cracks have emerged within the hardline movement, and many have expressed regrets for supporting Ahmadinejad. Gholam-Ali Haddad Adel, the influential conservative and father-in-law of Mr. Khamenei’s son, Mojtaba, was quoted saying “God regrets creating Ahmadinejad.” This has provided Mr. Khamenei with flexibility for maneuvering, even though he should take the lion’s share of blame for what happened during the Ahmadinejad administration.

Mr. Khamenei’s support for the nuclear negotiations is not, however, indefinite. The Rouhani administration must be able to show tangible results to the nation, and demonstrate that it did not cross the red lines that Mr. Khamenei has set for the negotiations, namely, recognition of Iran’s right to peaceful use of nuclear technology, particularly uranium enrichment. Thus, talk of dismantling a major part of Iran’s nuclear infrastructure, espoused by the neocons, as well as Israeli and Saudi Arabian lobbies in the United States, will also not go anywhere. Iran will not agree to it, but time and again it has demonstrated its willingness to make major concessions and to follow a prudent approach, only to be rebuffed by the United States and its allies. Asking Iran to give up a major part of its nuclear infrastructure is tantamount to demanding that it surrender its sovereignty and national rights. It will not happen.

As the author has emphasized repeatedly—here, here, here, and here—if Washington is interested in a diplomatic resolution of the dispute with Iran, which in turn will have a tremendously positive effect on peace and stability in the Middle East, especially in Syria, Iraq, Lebanon and Afghanistan, it should recognize the Rouhani administration’s domestic constraints, and offer compromises that President Rouhani can take home and demonstrate to his nation, including the hardliners, that diplomacy with the U.S. can work. That would also ensure continuation of Mr. Khamenei’s support for Rouhani, and marginalizing the hardliners.

Iran analyst Muhammad Sahimi, a Professor at the University of Southern California, is the editor of the website Iran News & Middle East Reports.