Rand Paul is dropping out of the race for the White House. With him goes the most substantial critic of the NSA in the Republican field.

Paul's libertarian position often put him at odds with other GOP candidates, who, during debates and public statements, tried to out-hawk other candidates on national security issues. In one particularly memorably debate, he traded jabs with Chris Christie, a former federal prosecutor who proudly said that he was "the only person on this stage who's actually filed applications under the Patriot Act." Paul responded by saying he wanted "more records from terrorists, but less records from innocent Americans."

The remaining contenders for the presidency take widely varying stances on NSA surveillance, from supporting some minor changes (Kasich) to planning an expansion of surveillance powers (several others) to dismantling the agency's program (Sanders). Still, no one else has made surveillance an issue on the same level as Paul. Here's a brief recap of the candidates' positions:

Donald Trump: Trump has said he tends to "err on the side of security" and would be "fine" with restoring parts of the Patriot Act that were lost when the USA Freedom Act was approved. "I assume when I pick up my telephone people are listening to my conversations anyway, if you want to know the truth," he Trump has said he tends to "err on the side of security" and would be "fine" with restoring parts of the Patriot Act that were lost when the USA Freedom Act was approved. "I assume when I pick up my telephone people are listening to my conversations anyway, if you want to know the truth," he once said . "It's a pretty sad commentary."

Ted Cruz: Cruz notably voted for the USA Freedom Act, which was seen as at least a small curb on NSA spying, but has argued that the bill Cruz notably voted for the USA Freedom Act, which was seen as at least a small curb on NSA spying, but has argued that the bill effectively increased the NSA's powers, even though it moved control of the records themselves out of the agency's hands.

Marco Rubio: Rubio sparred with Cruz over his vote on the Freedom Act, but ultimately argued for a different route to the same goal. The Freedom Act, he said, would unnecessarily hamper NSA spying. Previously, Rubio said he supported a permanent extension of the NSA's mass surveillance capabilities.

Jeb Bush: Bush has often suggested that the NSA's powers do not go far enough. He has supported an expansion of the agency's surveillance abilities.

Ben Carson: One of the more vigorous opponents of surveillance, Carson One of the more vigorous opponents of surveillance, Carson has said that "the mass collection of data is an intrusion of the Fourth Amendment rights of all Americans." He has also said that he supports forcing security agencies to get a court order before spying.

Chris Christie: Christie has repeatedly brought attention to his role as US Attorney for New Jersey, and has argued for an expansion of the NSA's powers.

John Kasich: Staking out a relatively moderate position compared to other GOP candidates, Kasich has called for a "balance" between surveillance and civil liberties, and Staking out a relatively moderate position compared to other GOP candidates, Kasich has called for a "balance" between surveillance and civil liberties, and broadly supported curbs on the mass collection of phone records.

Carly Fiorina: Although no longer a major contender for the GOP nomination, Fiorina has been extremely notable for her support of the NSA during her run. She said that, as CEO of HP, she Although no longer a major contender for the GOP nomination, Fiorina has been extremely notable for her support of the NSA during her run. She said that, as CEO of HP, she hand-delivered servers to the NSA when the agency needed them.

Hillary Clinton: Clinton Clinton endorsed the USA Freedom Act and has called for more transparency in the NSA, but has been seen as quiet on the issue

Bernie Sanders: Sanders has Sanders has long been critical of NSA surveillance, and supported restrictions on the agency's capabilities. Like Paul, he voted against the USA Freedom Act, arguing that it did not go far enough.

Regardless of position on the issue, no candidate seems to have tried to build a platform on NSA surveillance in the same way as Paul, who frequently brought up the NSA at debates and in Congress. With him gone, it's possible the issue may be pushed further into the background.