House Foreign Affairs Committee Chairman Ed Royce (R-Calif.), left, talks with the committee’s ranking member, Rep. Eliot Engel (D-N.Y.), during a hearing on the Iran Terror Finance Transparency Act. The committee is one of several leaning into Tehran with markups of bills and oversight hearings on the Iran nuclear pact this week. (AP Photo/Manuel Balce Ceneta)

The Iran deal’s opponents couldn’t pick apart the nuclear pact before it was implemented, but just weeks later, lawmakers are regrouping to come after Tehran in every other way they can.

In this week alone, lawmakers will gather for at least five separate committee meetings specifically dedicated to reviewing Iran’s actions ranging from its compliance with the nuclear pact to its dedication to locating and freeing still-missing former FBI agent Robert Levinson, who disappeared in Iran in 2007. Top U.S. intelligence officials were grilled Tuesday in two additional hearings for their take on the threat posed by Iran.

And later this month, senators are expected to roll out a series of bills to bring the greater weight of more non-nuclear sanctions down on Tehran, seeking to punish Iran for everything from recent ballistic missile tests to pervasive human rights abuses.

[With Iran deal in place, key senators look to slap new sanctions on country]

President Obama describes why Iran's fulfillment of the nuclear deal is important. He says, "Most importantly, we've achieved this historic progress through diplomacy without resorting to another war in the Middle East." (The White House)

Director of National Intelligence James Clapper addressed Iran at a hearing Tuesday on global security threats, warning that there are “many other things” Iran could do “in a nuclear context that serves to enhance their technology and their expertise,” especially in the area of research and development.

However, he also said he was “confident” that U.S. intelligence would be able to detect any serious violation or deviation from the nuclear accord.

In September, the Senate rejected an attempt to derail the nuclear pact on a largely party-line vote, while the House passed a measure to stall the deal, also carried by Republican votes. But since then, demands for oversight of the agreement and pushback against the deal have been more bipartisan, with some Democrats who voted against the deal signing on to efforts to ensure Iran stays in line.

[Democrats, frustrated with Obama on Iran, float new sanctions proposals]

“I don’t think it’s helpful to keep having bills that try to abrogate or get rid of what’s already been negotiated. But what we do need to focus on now is holding Iran’s feet to the fire,” said Rep. Eliot Engel (D-N.Y.), the ranking member on the House Foreign Affairs Committee, which this week is grilling the Treasury Department’s top sanctions official and its lead Iran negotiator about the nuclear pact.

A House Foreign Relations subcommittee will also mark up a bill calling on Iran to live up to its promises to shed light on Levinson’s disappearance. Iran has denied having Levinson in custody, but officials in Tehran are suspected of knowing more about his case than they are letting on.

The Senate Foreign Relations Committee will consider a similar Levinson-related measure this week as well.

The resumed assault on Iran comes as the Islamic Republic heads toward parliamentary elections for the 290-seat Majlis — one of the few directly elected governing bodies in the country. Many Republicans have argued that the Iran deal will only embolden Iranian hard-liners to take actions such as demanding “ransom” for American prisoners and spending more on terrorism.

Some experts have predicted that the Feb. 26 elections will serve as an early barometer of how Iranian sentiment is swaying in the wake of the Iran deal, whether toward moderates or more hard-line conservatives. Iran’s Guardian Council has already blocked several reform-minded candidates from participating.

Lawmakers, even those who supported the deal, have long been worried that Iran would take whatever opportunity it could to cheat at the margins of the nuclear deal. They insist that the United States has to be extra vigilant about enforcing non-nuclear sanctions to prevent Iran from attempting more egregious violations that might impact the nuclear deal.

Even Democrats complain that the administration did not move fast or hard enough to slap sanctions on Iran in the wake of two reported ballistic missile tests in apparent violation of U.N. Security Council resolutions.

But Congress has yet to take up any new sanctions legislation, despite apparent unity around the idea of at least reauthorizing the Iran Sanctions Act, the law that lays out a regime of nuclear, missile and terrorism sanctions on Iran’s trade, energy, defense and banking sectors.

Though the Obama administration has waived certain provisions of that law in light of the now-implemented nuclear deal, many lawmakers believe it is necessary to keep the measure alive in case the United States has to avail itself of the deal’s “snapback” option should Iran break its obligations under the deal.