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Top Republican senators urged President Obama on Saturday to hold the suspect captured in the Boston Marathon bombing as a potential enemy combatant -- denying him a government-appointed attorney and other legal rights under the “Law of War” so investigators can learn about other possible attacks.

After his capture Friday, bombing suspect Dzhokhar Tsarnaev was not read his Miranda rights, which essentially state those arrested have a constitutional right to be told information they give to officials can be used against them.

However, the public safety exception that allows suspects to be questioned without being read those rights expires 48 hours after the arrest.

“The events we have seen over the past few days in Boston were an attempt to kill American citizens and terrorize a major American city,” Sens. Lindsey Graham, South Carolina; John McCain, Arizona; and Kelly Ayotte, New Hampshire, said. “The suspect, based upon his actions, clearly is a good candidate for enemy combatant status. We do not want this suspect to remain silent.”

They were joined in the statement by New York Republican Rep. Peter King.

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Tsarnaev, 19, was captured in Watertown, Mass., about eight miles from the bombing site. He remains in a hospital in serious-but-stable condition with two gunshot wounds.

He will be interrogated by the Obama administration's High Value Interrogation Group.

Justice Department officials tell Fox News they hope to file charges against Tsarnaev by the end of the day Saturday.

Federal public defenders said they have agreed to represent Tsarnaev.

Miriam Conrad, the federal defender for Massachusetts, says her office expects to represent Tsarnaev after he is charged.

Conrad said Tsarnaev should have a lawyer appointed as soon as possible because there are "serious issues regarding possible interrogation."

The Republican lawmakers also said: "We remain under threat from radical Islam and we hope the Obama administration will seriously consider the enemy combatant option. We are encouraged our high value detainee interrogation team is now involved … .A decision to not read Miranda rights to the suspect was sound and in our national security interests.”

President Obama in the immediate aftermath of the bombings declared them an “act of terrorism.” And he vowed after Tsarnaev’s capture Friday to get answers but has yet to say whether the administration will use the combatant status.

The second suspect, Tsarnaev’s 26-year-old brother, Tamerlan Tsarnaev, was killed early Friday morning in Watertown in a shootout with police.

Two bombs set off Monday afternoon near the marathon finish line killed three people and injured 176 others.

The president on Friday night said the victims “deserve answers.”

“We will determine what happened,” he said. “We will investigate any association that these terrorists may have had.”

The American Civil Liberties Union expressed concern about Tsarnaev being questioned without being read his Miranda rights.

Group Executive Director Anthony Romero said Saturday the exception applies only when there's a continued threat to public safety and is "not an open-ended exception" to the Miranda rule.

The Obama administration has a range of legal options in the case, including seeking the death penalty.

The administration has indicated it intends to move quickly to build a criminal case.

Prosecution in federal court would seem a natural course for an administration that previously won a life sentence against Umar Farouk Abdulmutallab of Nigeria for trying to blow up a packed jetliner using a bomb sewn into his underwear on Christmas Day 2009.

The administration also will put Usama bin Laden's son-in-law on trial in January on charges that he conspired to kill Americans in his role as al Qaeda's chief spokesman.

As a U.S. citizen, Tsarnaev could not be tried by a military commission under current law; the only option for prosecuting an American is in civilian courts. A federal official with knowledge of the case said Tsarnaev was naturalized as a U.S. citizen in September 2012. The official was not authorized to speak publicly about details of the case and requested anonymity.

King told Fox News before Tsarnaev’s capture that his Miranda Rights could be denied.

“I believe he can be interrogated under the public safety exception of the Miranda ruling because clearly life and death can be involved here,” he said. “I feel confident the FBI has the right to interrogate him.”

The lawmakers were followed by Sen. Saxby Chambliss of Georgia, the top Republican on the Senate Intelligence Committee, who said: "I am disappointed that it appears this administration is once again relying on Miranda's public safety exception."

But Rep. Adam Schiff, D-Calif., a former federal prosecutor and member of the House Intelligence Committee, told Fox News the administration should ignore "hasty calls to treat the suspect as an enemy combatant."

The Associated Press contributed to this report.