John Bolton, a respected GOP voice on foreign policy, is considering making an endorsement in the Republican presidential primary.

“I’m not the S&P 500 rating system. While I spent most of 2015 focused on having a substantive debate on foreign policy, I am now observing the individual candidates, their foreign-policy stances, and whether or not he or she is prepared to be president on day one. If I feel it necessary to endorse a candidate during the caucus and primaries, I will,” Bolton says in a statement to National Review.

Bolton, the former US ambassador to the UN, raised just under $7 million last year for his PAC, his super PAC, and his nonprofit, the Foundation for American Security and Freedom, according to numbers provided first to NR.

Earlier this year, Bolton endorsed senators facing tough reelection races in several swing states, and his PAC donated to their campaigns. His super PAC may amplify that message: He is looking at running independent expenditure ads in those swing states crucial to Republican hopes not only for holding the Senate, but for winning the presidency — Wisconsin, Colorado, Iowa, Nevada, Florida, and Arizona. The super PAC is already running ads praising Republican senator Kelly Ayotte in New Hampshire.