Less than 48 hours after Donald Trump promised to issue an executive order requiring those who kill police officers to get the death penalty, the Republican presidential front-runner accused President Obama of overusing them.

Trump said at a town hall in South Carolina on Saturday that most people had not heard of executive action until Obama became president and began using the power to push through initiatives that Congress would not approve, including several related to immigration.

"Usually you had to get Congress, you had to talk the senators into it, you had to talk your congressman into it, you had to deal with all the people. … You have your three branches, and you talk to them, and you get something passed -- and there's compromise, and sometimes we don't like to compromise," Trump said during a town hall in Aiken, S.C., that was moderated by South Carolina Attorney General Alan Wilson.

"But that's the way the system is supposed to work," Trump said. "And then, all of a sudden, I started hearing: 'Oh, well, he tried. He can't do it.' And boom. And another one, boom. And you have these executive actions. I don't even think he tries any more. I think he just signs executive actions."

If he's elected president, Trump said that within an hour of taking the oath of office -- but possibly within two minutes -- he would undo many of Obama's executive orders, especially the immigration ones.

But Trump has already promised to issue at least one executive order of his own. Trump said in New Hampshire on Thursday night that he would quickly issue an executive order that calls for the death penalty for anyone who kills a police officer. He made this announcement while accepting the endorsement of a regional police union that has been pushing this proposal. It's unclear how Trump would word such an order -- his staff has not returned requests for comment -- or if there's a legal way for a president to make such a change without congressional approval.