TEHRAN, Iran » The chants of "Death to America" and the burning of American flags in the streets are as familiar a part of life here as air pollution and traffic jams. With the United States and Iran on the verge of a potentially historic nuclear accord, however, there has been a distinct change in tone: The anti-Americanism is getting even more strident.

The rising levels of vitriol have been on display this week in the buildup to the annual anti-Israel extravaganza coming this Friday.

"We march not only against Israel," the influential Ayatollah Ali Jannati told the Fars News Agency of the annual rally on the last Friday of Ramadan in Iran and other Muslim countries. "It goes far beyond that. We also march against the arrogant powers," Europe and, particularly, the United States.

The underlying cause for the heightened display of anti-Americanism, analysts say, is the growing likelihood that Iran and its Western negotiating partners will sign a nuclear accord, opening the possibility of improving relations with the Great Satan, the United States.

"Anti-Americanism is a pillar of our system," said Nader Karimi Joni, a reformist journalist. "Now that we are in direct talks with the United States, the reaction is to oversell anti-Americanism, to emphasize that they continue to be the enemy."

Negotiators continued their work in Vienna on Wednesday, trying to iron out last-minute wrangles over a weapons embargo, missile sanctions, inspections and the pace of relief from economic sanctions. Despite some reports that the Obama administration was ready to extend the deadline for negotiations indefinitely, U.S. officials in Vienna said they were pressing to conclude negotiations this week.

If a deal is completed, the existing tensions between Iran’s two political factions are bound to increase, analysts say.

"We can expect a lot of anger, the government will be accused of treason, betrayal of Islam, caving in to American pressure and so on," said Farshad Ghorbanpour, a political analyst close to the government. "They will not sit back and say, ‘OK, no problem.’ They don’t want relations."

Those in Iran’s divided political system hoping for better relations with the West have always faced off with powerful groups opposing any rapprochement.

When the reform-minded President Mohammad Khatami advocated better relations with the U.S. in 2000, hard-liners threw stones at buses carrying American tourists. The opposite occurred in 2006, during the presidency of Mahmoud Ahmadinejad. In that case, a government-sponsored conference denying the Holocaust was criticized by Iranian reformists, who argued that Iran needed to join the world, not alienate it.

Since its election in 2013, the government of President Hassan Rouhani has been promoting better relations with the West. Publicly admitting that the state’s coffers are empty and that the oil industry needs hundreds of billions of dollars in investments, the new government has been welcoming interest from international and U.S. oil companies, airplane manufacturers and investors of all sorts, beckoning them to come to Iran after a deal is clinched.

This is what Iran’s conservative clerics, lawmakers and commanders fear most, because it puts the country on the road to normalization of relations with the United States.

"What will be left of our revolution, of our position in the Islamic world if we start relations with a country devoted to oppressing us and many others?" asked Alireza Mataji, an organizer of anti-American rallies. "We will not let America destroy us by an iron fist covered in a velvet glove."

Knowing they are increasingly outnumbered, analysts say, they are using the many means under their direct control to reinforce their message.

State television, the main tool for disseminating official views, still reminds viewers day in and day out of all the evil acts and "crimes" committed by the United States. Every public event — the annual anniversary of the revolution, parliamentary elections, military parades — provides another opportunity to pound away at the official message of the founder of the Islamic Republic, Ayatollah Ruhollah Khomeini, that "America needs to be punched in the mouth."

Saeed Laylaz, an economist close to the government and a supporter of better relations with the U.S., said, "Hard-liners are very skilled in manipulating anti-American sentiments. Right now they are preparing the grounds for their future offensive."

Those opposing relations are not against a deal per se. They are interested in solving the nuclear issue — but on Iran’s terms. They also agree the country needs investments, but from nonpolitical actors like oil companies, not from Starbucks and Disney.

"Those who think that even after a deal we will open our borders and change are very, very wrong," said Hamidreza Taraghi, a political analyst close to the supreme leader, Ayatollah Ali Khamenei. He said that European and Asian investors were free to come to Iran, because they "respect local culture" and make their money and get out. The United States is different, he said. "Their aim is — and they are not able — to overthrow our Islamic system, by war or by cultural offensive."

For Friday’s Quds Day rallies, the annual protest against the Israeli occupation of Palestine (Quds is the Arabic name for Jerusalem), Iran’s Coordination Council of Islamic Propaganda released the preferred slogans on its website on Tuesday.

"Please shout the messages of all the times, which are ‘Death to America,’ ‘Death to Israel,’ ‘Death to global arrogance,’ and ‘Death to international Zionism,’ " the website read.

"Of course we will keep on shouting such slogans after a deal," said Taraghi. "We will make sure that nothing will change."