What does he mean by “even in the GOP”? The GOP opposed helping the Libyan and Egyptian Muslim Brotherhood and arming the Syrian anti-government forces.
The NeoCon Republicans were the first to want to intervene in Libya. The Realist Republicans opposed. Bob Gates, Henry Kissinger, and James Baker very publicly opposed. It was only after the Liberal Interventionist democrats negotiated the multilateral agreement that Obama intervened. The multilateral agreement was set up by Susan Rice, Samantha Power, and Hillary.
The NeoCons praised Obama for intervening. Bill Kristol proclaimed Obama to be a "Born Again NeoCon". Of course they criticized him too, saying he should have gone in immediately instead of waiting for the multilateral agreement. And since Obama went in multilaterally, they complained he was leading from behind. Hardcore NeoCon John Bolton complained because Obama didn't put boots on the ground in Libya.
As for arming the Syrian rebels, look at the Senate Foreign Relations Committee vote to arm the rebels in May of 2013. That passed the committee 15 to 3. The NeoCons(R), the Realists(R & D), and the liberal interventionists(D) voted yes. The 3 no votes were the 2 antiwar dems(Udall and Murphy) plus the GOP isolationist Randy Paul. After that vote, Mike Lee joined Paul, Udall, and Murphy on legislation to block the arming.
Its not about a Republican versus Democrat. Its about NeoCons, Realists, and Liberal Interventionists.
On the recent issue of imposing additional sanctions on Iran before the negotiations played out, The NeoCons(led by Sen Kirk) and the Liberal Interventionists(led by Sen Menendez) wanted the additional sanctions. The Realists led by Sen Feinstein(D) and Sen Corker(R) opposed the additional sanctions. The antiwar dems and GOP isolationists also opposed the sanctions.