Washington ? The Supreme Court has set the stage for a series of rulings on the reach of presidential power, decisions that could arrive just as voters focus on whether to endorse President Bush and his strong style of executive leadership.

Since November, the justices have voted to take up five cases that test the president’s power to act alone and without interference by Congress or the courts. They involve imprisoning foreign fighters at overseas bases, detaining U.S. citizens without charges in military brigs, preserving the secrecy of White House meetings, enforcing free-trade treaties despite environmental concerns and abducting foreigners charged with U.S. crimes.

The case taken up Friday may be the broadest of all. Two years ago, the White House said the president had the power to designate U.S. citizens “unlawful enemy combatants” and keep them in secret military custody, without filing charges or allowing them to plead their innocence.

Bush’s lawyers said the “time-honored laws and customs of war” gave the commander in chief the power to detain captured soldiers. But not until recently had a president contended that his military power extended to arresting Americans on U.S. soil.

In December, a federal appeals court in New York ruled the president overstepped his authority in the case of Jose Padilla, a New York-born Muslim who was taken into custody at Chicago’s O’Hare Airport and imprisoned in a military brig in South Carolina. The judges said the administration must either charge him with a crime or release him.

The justices announced Friday they would take up the issue and rule on whether the president has the constitutional power to bypass the courts and keep U.S. citizens in military custody.

“The Supreme Court appears poised to issue the most important set of decisions about the scope of presidential power since World War II,” said Deborah Pearlstein, director of the law and national-security program for the Lawyers Committee on Human Rights. She said the high court’s move “sends a clear message that the president’s power to detain U.S. citizens is subject to certain limits.”

“This administration has massively asserted presidential power unlike any since Nixon,” said Alan Morrison, a lawyer for Public Citizen, a liberal group that has opposed Bush in several pending cases. “The thread running through all these cases is that (administration officials) don’t believe the part of separation of powers that has checks and balances in it.”

The Bush administration’s lawyers assert that since the Constitution made the president the commander in chief, he has the power to act.