Jeb Bush stressed the idea of “proven leadership” Thursday for “serious, dangerous times” that include terrorist threats from the Islamic State.

“They have declared war on us, and we need to declare war on them,” the former Florida governor told a forum sponsored by the Republican Jewish Coalition.

The Islamic State has taken over territory in Syria and Iraq — “a caliphate the size of Indiana” — and has to be stopped with leadership from the United States, Bush said.

The son and brother of previous presidents, Bush also criticized the Iranian nuclear agreement and pledged to back Israel in peace talks with the Palestinians.

“We must not pressure Israel on settlements until Palestinians recognize Israel and it borders,” Bush said.

Bush also praised President George W. Bush’s policies toward Israel, telling the crowd that “I got a damn good brother.”

Once considered a front-runner for the Republican presidential nomination, Bush now lags in Republican polls. He told members of the Republican Jewish Coalition that they should back his “ideas and leadership skills” and question some of the “big personalities on the stage,” an apparent reference to front-runner Donald Trump.

Predicting a comeback, however, Bush said that “I’m going to win New Hampshire first.”

Bush also claimed he would be a better general election candidate against the Democratic opponent.

“I will take it to Hillary Clinton and I will whoop her,” he said.