Former Florida Gov. Jeb Bush and former Puerto Rico Gov. Luis Fortuno converse during an event at the Metropolitan University in San Juan, Puerto Rico, on Tuesday. (Erika P. Rodriguez/ For The Washington Post)

Former Florida Gov. Jeb Bush forcefully defended his positions on immigration and taxes on Thursday while taking several swipes at Republican lawmakers thinking about running for president.

Bush, appearing at a summit hosted by the National Review, grew combative at times and appeared to be lecturing the crowd on immigration reform, saying that the GOP needs to change its tone and position on how to tackle a vexing domestic concern.

Under questioning by moderator Rich Lowry, Bush insisted that he will decline to sign any "pledge" vowing to do or not do something as a candidate or as president. The question came up in regards to his refusal to sign the Americans for Tax Reform pledge on tax cuts.

"No," he said when asked whether he would sign Norquist's pledge. "But, I cut taxes every year, $19 billion. No one comes close to the record of tax cuts."

"If you served in the United States Senate over the last eight years, or six years, no tax cut has taken place," he added later. "...So anyone associated with Washington, D.C. can talk about this stuff, but places where the taxes have been cut are in places like Florida, where they were led by a conservative governor who thought this was important."

Bush also dismissed conservative criticism of his position on immigration reform, especially his belief that some of the roughly 11 million undocumented immigrants should be able to apply for a legal status if they meet certain criteria.

"I just think you’re wrong on immigration, to be honest with you," he said to Lowry, referring to both Lowry himself and the National Review's general position on immigration. "You might think I’m wrong and I respect you for it, but I just honestly believe that if we fix the legal part of it that’s not working we could grow our economy far faster and we’d be younger and more dynamic.

[Bush leans in to immigration reform in speech to Hispanic Christian organization]

"The world that some argue for is a world of declining population," he added. "It’s the world of Japan. It’s the world of Europe in decline. I reject that. America doesn’t do that well. America does, we’re at our best when you’re young, aspirational and dynamic. Maybe I’m stubborn, I’m willing to listen to other views on this and I’m hopeful about having a good dialogue about this, but I think I’m right about this. And if we’re going to grow economically, then we need to figure out how to get this fixed pretty quick."

Most especially, Bush once again said Republicans need to tread carefully when discussing immigration or risk losing the support of minority voters.

He said that on immigration, President Obama "uses this as a wedge issue and we always lose. We always lose on the political argument about tone and about all this. And he always wins or the Democrats always win if you think about having family be the driver of legal immigration rather than an economic driver. Delaying this is what he wants. He doesn’t want immigration reform.

"We’re going to turn people into Republicans if we’re much more aspirational in our message. And our tone I think has to be more inclusive as well," he added later.

Bush appeared at the National Review summit in Washington on the same day he visited the city for fundraisers. He's scheduled to travel to North Carolina on Friday before addressing South Carolina Republicans in Columbia on Saturday.