(CNN) Federal courts across the country have seen a flurry of activity over the last week as challengers of President Donald Trump's new travel ban race to block it before it ever goes into effect.

Trump signed a new executive order last week banning foreign nationals from six Muslim-majority countries from entering the US for 90 days and banning all refugees for 120 days. The new order excludes those with green cards and valid visas.

But the states that sued Trump over the original executive order have popped back to the surface with gusto, saying that merely changing who is exempted under the order doesn't make it constitutional and the new ban "differs only cosmetically."

On Monday,Washington and Minnesota -- two of the states that successfully blocked the original travel ban -- asked a federal judge to enforce his earlier ruling against the new travel ban as well. Other states have hearings scheduled for Wednesday -- just one day before the new travel ban is scheduled to go into effect.

Here are the cases to watch before the new executive order goes into effect on Thursday:

State challenges

One day after Trump signed the new executive order, Hawaii mounted the first legal challenge last Tuesday. Attorneys for the state argue that new executive order remains discriminatory and harms the economy, and have asked a federal judge to issue a temporary restraining order blocking several provisions of the new order. The Justice Department filed a 54-page response to that new challenge on Monday, arguing the new travel ban: (1) only applies to foreign nationals with no constitutional right to enter the US; (2) affords "more than ample process" for someone seeking admission through the waiver system; and (3) does not discriminate on the basis of religion, as "it no longer grants any preference for victims of religious persecution."

DOJ's filing also included a newly released letter from the heads of Homeland Security and DOJ supporting the travel ban.

"There are currently approximately I,000 pending domestic terrorism-related investigations, and it is believed that a majority of those subjects are inspired, at least in part, by ISIS," Homeland Security Secretary John Kelly and Attorney General Jeff Sessions jointly wrote in the letter.

"We expend enormous manpower and resources investigating terrorism-related activities of foreign nationals admitted to the United States. ... Furthermore, based on DHS data and the experience of its operators, nationals from these countries are more likely to overstay their visas and are harder to remove to their home countries."

The judge will hear oral arguments from both sides in Honolulu on Wednesday.

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Washington and Minnesota followed in Hawaii's footsteps last week, announcing that they, too, planned ask a federal judge in Seattle to halt the new travel ban. Attorneys in that case argue that the new executive order "purports to reinstate two provisions of the prior order" that US District Court James Robart blocked last month, and therefore, the new order must remain suspended as well.

"While the second executive order now excludes Iraqis, lawful permanent residents, and visa-holders from its travel ban, it bars entry for virtually all other individuals from the listed countries, including: relatives of US citizens; students who have been admitted to state universities but not yet received visas; prospective employees of state universities or private businesses who have been offered positions but not yet obtained visas; and students and employees who may need to renew their visas," attorneys argued in a court filing Monday.

"All of these individuals (and the institutions that wish to admit or hire them) are protected by this Court's injunction, but are nonetheless targeted and harmed by the second executive order."

Attorneys general from Maryland, Massachusetts, New York, Oregon and California confirmed they are also planning to join the lawsuit in Seattle.

The Justice Department declined to comment to CNN on the status of any ongoing litigation. But it filed a "notice" with Robart after the order was signed last week, claiming that the administration believes the new executive order "falls outside of the scope" of Robart's earlier ruling. The administration cited the substantial changes to the executive order, arguing that it "clarifies and narrows the scope of executive action regarding immigration, extinguishes the need for emergent consideration, and eliminates the potential constitutional concerns identified by the Ninth Circuit."

But late last week, Robart told everyone: not so fast.

He explained that the parties hadn't technically asked him to rule on any new request yet, and therefore, declined to resolve any of the outstanding issues until one side filed a procedurally proper motion under local and federal rules.

As a result, on Monday morning, the Washington state attorney general's office filed a proposed amended complaint along with a formal motion to enforce Robart's original preliminary injunction suspending the travel ban. But Robart rejected the states' request for an expedited hearing on the matter on Tuesday, and instead ordered the Justice Department to file a response Tuesday.

Additionally, the states filed nearly 50 new "declarations" from residents, educational institutions, businesses and religious organizations, which set forth many of the harms they claim to face under the new executive order.

Individual challenges

At least one of the individual challengers of the new executive order had success last Friday.

A Syrian "John Doe" plaintiff living in Wisconsin successfully argued that the new travel ban is preventing him from reuniting with his wife and child who are currently trapped in Aleppo. A federal judge in Madison acknowledged some "important differences" between the original executive order and the new one, but ultimately concluded this particular Syrian family faces "a significant risk of irreparable harm" given "the daily threats to the lives plaintiff's wife and child remaining in Aleppo, Syria."

As result, the judge issued a temporary restraining order blocking application of the new travel ban in this particular case, but not for any other families.

A federal judge in Maryland has also set a hearing on Wednesday morning to hear another challenge brought by refugee aid groups and several foreign nationals. They allege that many foreign nationals, including those from the six banned countries and refugees, have family in the US and will suffer "as a result of the delaying reuniting with their family members."

Finally, a lawsuit was filed by a private attorney on behalf of the "people of California," according to court documents last week. But it was not filed by the state attorney general's office and unclear whether the judge will allow the case to proceed. A similar lawsuit filed after the original ban was announced, but was quickly dismissed.

This story has been updated.