President Barack Obama is facing a liberal backlash over his hardline national security policy, which critics say is more extreme and conservative than that pursued by George W Bush.

The outrage comes after a week in which Obama’s nominee to be the next head of the CIA, current White House adviser John Brennan, faced a grilling from the Senate intelligence committee over his enthusiastic support of using unmanned drones to strike suspected Islamic militants all over the globe.

It also comes after a court hearing in New York in which numerous liberal activists and journalists argued that a new Obama law – the National Defence Authorisation Act (NDAA) – has dealt a serious blow to civil liberties by allowing American citizens to be detained indefinitely without trial.

Both developments also add to liberal frustration with an Obama administration that has ruthlessly cracked down on whistleblowers, especially on matters of national security, and failed to implement a promise to close down the Guantánamo Bay prison camp.

“If Bush had done the same things as Obama, then more people would have been upset about it. He is a Democrat though, and to an extent can get away with it,” said Daniel Ellsberg, who as a government official leaked the Pentagon Papers in 1971 and helped to expose the truth about the Vietnam war. Ellsberg is now one of the plaintiffs in the case against the NDAA and insists that the administration has used the law to give itself widespread and unconstitutional new powers: “We have been losing our guaranteed freedoms one by one.”

The government denies that the NDAA represents any sort of threat to ordinary citizens and has appealed against a judge’s ruling that it is unconstitutional, saying that the White House needs such powers to fight terrorism. However, critics say its use of broad language to define what constitutes a terrorist or what actions make up support for terrorist groups could drag in journalists, activists and academics. The case, which is currently on appeal in New York, could go all the way to the supreme court. Liberal film-maker Michael Moore has attacked the Obama administration for backing the NDAA. “In order to protect us from terrorism, the government is taking away our constitutional rights,” said Moore, who made the anti-Bush documentary Fahrenheit 9/11.

But much of the real focus of liberal ire has been the administration’s huge expansion of its use of drones. Brennan has been at the forefront of that programme and its “kill list”, maintained by the White House, which targets specific Islamist militants in countries such as Afghanistan, Yemen, Pakistan and Somalia. The programme is backed by military and intelligence chiefs but independent groups that track the attacks say it has caused hundreds of civilian casualties. It has also been criticised for killing radical cleric Anwar al-Awlaki and his 16-year-old son, who were American citizens.

The administration is facing intense pressure to make public secret documents that lay out its legal rationale for the killings. But it has so far resisted, prompting many groups to compare Obama’s national security policy to Bush’s drawing-up of secret legal memos justifying torture techniques such as waterboarding. “The parallels to the Bush administration torture memos are chilling,” said Vincent Warren, executive director for the Centre for Constitutional Rights. “Those were unchecked legal justifications drawn up to justify torture; these are unchecked justifications drawn up to justify extrajudicial killing.”

Obama’s policy has put him in political alliance with some strange bedfellows. Three hawkish Republican senators, including 2008 presidential candidate John McCain, filed a brief in support of the NDAA law during the court hearing. They defended Obama’s stance on national security grounds.

Another source of anti-Obama anger for liberal groups has been the administration’s attitude to whistleblowers. Obama has used an arcane piece of first world war legislation, the 1917 Espionage Act, six times to pursue cases, more than all his predecessors combined. One case involved former CIA agent John Kiriakou, who was prosecuted for leaks after he went public with allegations of torture of suspects. He has now been jailed, which critics point out means that, while no one has been prosecuted for torture, a man who sought to end the practice is behind bars. Jesselyn Radack, a director of the Government Accountability Project, which helps to defend whistleblowers, said using the Espionage Act was a strategy designed to intimidate those exposing government wrongdoing. “They are being labelled enemies of the state,” she said.

One of those is Thomas Drake, a National Security Agency worker who has been prosecuted after leaking details of waste and overspending at the organisation. The case against him collapsed in 2011 after he agreed to plead guilty to a misdemeanour, and the government dropped more serious charges that could have jailed him for 35 years.

But the experience has left Drake a strident critic of the administration. At a meeting in Manhattan last week where numerous civil rights activists including Ellsberg and Moore gathered to discuss the NDAA case, Drake said that first Bush and then Obama had increasingly used secret powers to carry out national security policy since the World Trade Centre terrorism attacks of 2001.

“Everything that has happened since 9/11 has simply increased the power of that secret government. The constitution for them is just a piece of paper. It is an inconvenient truth,” he said.