Washington (CNN) President Donald Trump's top national security advisers are encouraging him to comply with the terms of the 2015 Iran nuclear deal and renew temporary waivers for US sanctions against Iran ahead of Friday's key legal deadline, US officials told CNN.

The renewal of those waivers -- which provide relief from US sanctions that are not set to expire for several years -- must occur every 120 or 180 days to keep the US a party to the deal and thus not violate the accord.

Trump will meet Thursday with his national security team to review the waiver issue, two senior State Department officials told CNN, adding that both Secretary of State Rex Tillerson and Defense Secretary James Mattis have recommended the President sign the waiver to give the Senate time to amend the legislation.

"He is advising the President to give this process more time," one official said of Tillerson. "The argument is the process has not become completely undone and we should keep it that way."

The officials said it is still unclear whether Trump will waive the sanctions, but expressed hope that he will do so.

A decision not to renew the waivers could be viewed by Iran and European allies of the US as a violation of the agreement and further derail any hopes of salvaging the deal.

The hope inside the White House is to get Trump to sign the waiver one more time, according to a source familiar with the thinking. But what Trump says while doing it -- what markers he lays down for Iran and other signatories -- remains to be seen, the source said.

Last week, a senior official told CNN that the administration was still discussing whether the President should waive the sanctions and continue to comply with the terms of the nuclear deal.

The President likely won't make up his mind until the eleventh hour, as he has with past Iran deal deadlines, the official said, adding that the administration is mindful that if Trump does not agree to waive the sanctions, the Iranians will claim the US has broken the terms of the nuclear deal and international opinion would side with Iran, not the US.

A source at the White House told CNN on Wednesday that they expect Trump to sign the waivers but cautioned, "You never know what's going to happen once it's on the President's desk."

Trump waived the sanctions at the last deadline but has since decertified Iran's compliance with the nuclear deal, accusing the country of committing "multiple violations of the agreement," despite the fact that the International Atomic Energy Agency, America's European allies and even his own government said Tehran is complying with the 2015 deal.

Trump is expected to once again decertify Iran's compliance at the mid-January deadline, just as he did in October, a senior administration official told CNN last week.

But his decision regarding the sanction waivers remains less clear, especially considering his threat in October to unilaterally kill the nuclear deal if Congress and US allies fail to take steps toward strengthening it.

A State Department official said that in the past the waivers were not the primary problem for Trump, but rather the certification on whether Iran was meeting its obligations under the deal.

Because the President has already decertified, the official said, there is "no reason for the waiver to be a flashpoint" for him, but the administration has fueled speculation by saying it is keeping "our options open" as far as sanctions against Iran are concerned.

The official noted there are also other ways to sanction Iran for its behavior outside the nuclear deal, such as its ballistic missile activity and its actions in Yemen and elsewhere.

On Friday, Tillerson reasserted the administration's intent to "look at the totality of Iran's actions and behaviors" and suggested that further non-nuclear sanctions were in the works unless "Iran alters its behavior."

What is in the works?

One senior official told CNN last week that the administration is also still working with European partners to make changes to the Iran deal and that they've "made some progress."

Yet European diplomats have been very vocal in their opposition to any US actions that would jeopardize the nuclear agreement -- known as the Joint Comprehensive Plan of Action -- including failure to meet the upcoming sanction waiver deadlines.

The administration is well aware of the concerns held by the European signatories, one diplomat told CNN last week.

Arab allies have also made the case to the administration to sign the waivers and keep the focus on Iran's other behavior in the region, such as ballistic missiles, support for groups like Hezbollah and Houthis, and human rights, three Arab diplomats said.

"We have told the White House that if the President focuses on the JCPOA and reimposes the sanctions, he risks losing support from the international community, especially Europe, for going after Iran," one senior Arab diplomat told CNN.

The White House and lawmakers continue to discuss measures that would address key concerns outlined by Trump in October and "have a legislative fix," according to the chairman of the Senate Foreign Relations Committee, Sen. Bob Corker.

"It would deal with some of the problems that exist in the deal, where they can move below a one-year breakout very quickly, and it resolves that at least domestically with their own policies," the Tennessee Republican told CNN on Wednesday, noting that he continues to work with fellow lawmakers and Trump's national security adviser, H.R. McMaster, on the issue.

But Corker admitted that he does not know if the legislation will be enough to keep the US in the nuclear agreement.

"The question is, does the President himself, even with this, want to stay in the deal?" he said. "I think that decision could be forthcoming."

Corker and senior administration officials made the case to Trump on Air Force One on Monday to issue the waivers, while giving a status update about the bipartisan bill they are developing, sources said.

Trump, the sources said, did not tip his hand about what he will do.

Fellow Republican Sen. John Cornyn also said Wednesday that he also does not know what the President is going to decide on Friday.

"I don't know what the President is going to do on it, I think we need to take a more holistic view and not just focus on one aspect of their military," the Texan said, echoing Trump's fundamental approach to the issue.

The Obama administration excluded other deep disagreements with Iran from the deal, reasoning that its threat would be much worse if it were able to race to a nuclear weapon in a matter of months.

Sen. Ben Cardin of Maryland, the ranking Democrat on the Foreign Relations Committee, admitted that he is nervous ahead of Friday's deadline.

"Because the stakes are pretty high, it's certainly a matter of anxiety. No question," he told CNN.

While Cardin has not seen the legislation being worked on by Republicans and the administration, he did say he has told McMaster that "there is a framework that can work" but also that the Democrats are going to want input as well.

Protests complicate Trump's decision

The recent protests in Iran have further complicated matters for Trump and his top advisers as the administration weighs options for increasing pressure on the regime.

One US official told CNN that there is a debate on whether reimposing sanctions would undercut the case of Iranian protesters who criticized the government's handling of the economy.

"If President Trump reimposed the sanctions, the government can blame the US for its economic problems," the official said. "We want to keep the focus on the regime and its draining of the economy."

Iran's ambassador to the United Nations seemed to do just that during a controversial UN Security Council meeting last week after the US requested an emergency session to discuss the protests.

"The move by the United States to bring to this council protests in Iran by some of our citizens for their legitimate grievances -- some exacerbated by none other than the US itself in its dereliction of its obligations under the Joint Comprehensive Plan of Action -- is an abuse of its power as a permanent member, and an abuse of the council itself," Iranian Ambassador to the UN Gholamali Khoshroo said.

Sen. Dianne Feinstein said Wednesday that reimposing the sanctions that were waived under the terms of the nuclear deal would "undermine the protesters" Trump "claims to support."

"Over the past few weeks, we've witnessed the Iranian people protesting in the streets against their government and its policies," the California Democrat said. "Lifting sanctions helped expose their government's corruption and mismanagement of its economy, and reimposing them now would be turning our back on the Iranian people."

Trump has used the Iranian anti-government protests as an opportunity to slam the nuclear deal ahead of this month's legal deadlines, prompting a direct response from key European allies.

UK Foreign Minister Boris Johnson told the British Parliament on Tuesday that "it is vital that the people of Iran and government of Iran should understand that we in this country support right to peaceful demo within the law." He also urged the UK's "friends in the White House not to throw away" the nuclear deal.

Arab diplomats have told CNN that their discussions with the Trump administration regarding Iran center on how to take advantage of the protests to keep up the pressure on Tehran.

"The protests have given us the ability to focus on Iran's behavior in the region," one of the Arab diplomats said. "Now that we have the world's attention we don't want don't lose it. Sign the waiver, focus on the missile programs, the human rights, Hezbollah, the Houthis. Iran's behavior is the problem. Don't allow it to shift and be about the United States."