I spoke to former U.N. ambassador John Bolton this morning about his endorsement last night of Mitt Romney. He said he has been contemplating for some time whether to endorse a GOP candidate. “I just thought you oughta decide at some point,” he said. He said it was critical that he back someone who could beat President Obama. “I do think Governor Romney is the best candidate to defeat Obama. Jim Baker [former secretary of Treasury and state] gave me some great advice: ‘Keep your eye on the prize.’ ” By that, Bolton means that if Republicans can beat Obama in November, everything else is irrelevant.

It comes at an awkward time for Newt Gingrich, who has said Bolton would be his ideal secretary of state. Gingrich is facing a firestorm of criticism over his attacks on Romney’s experience at Bain Capital. Bolton’s name adds to the long list of hard-core Republicans who are lending support to Gingrich’s nemesis.

Bolton also told me about what voters should look for in a presidential candidate, basing his opinions on his years in government. “For judges, we talk about judicial temperament. For this, [Romney] has executive branch temperament and what you need in a crisis.” It is that lack of executive experience and temperament, Bolton said, that is so troubling in Obama. “Obama thinks being president consists of giving speeches.” But, Bolton said, what is critical is some broader executive experience as a governor, senior federal official or in the private sector. “It means starting at ‘A’ and getting to ‘B,’ ” he told me. He joked that that doesn’t mean “saying I want to get from A to B. That’s a speech.”

Meanwhile, he remains deeply troubled about the Obama administration’s approach in the Middle East. In Syria, he argued, “You can’t take [Bashar al-] Assad on unless you’re willing to take on Iran.” He’s convinced that Tehran is willing to invest plenty and see plenty of Syrian blood spilled to keep its surrogate in power. Quoting former secretary of state Al Haig, he said, “We should go to the source.”

Unfortunately, we are doing, it seems, everything to convey weakness to the Iranian regime. He contends, “[The Obama administration] still thinks they can negotiate with Iran over its nuclear weapons system.” In order not to ruffle their feathers, the administration then acts meekly. Referencing the assassination of another Iranian nuclear scientist, Bolton remarked, “Hillary [Clinton] said we had nothing to do with it whatsoever. Traditionally, we say, ‘We don’t comment on alleged intelligence activities.’ Why go out of your way to say ‘Not us’? It’s because they are afraid of retaliation. But when she goes out of her way [to deny U.S. involvement], it reflects fear.”

He contends that the Obama administration acts as if it makes no difference in Iran’s calculations if it sees the United States pulling troops out of Iraq, negotiating with the Taliban or reacting so nervously about the killing of the Iranian scientist. He attributes Obama’s lack of understanding about the implications of our actions to one of two things. “Either they are terribly inexperienced and naive or they just don’t care.” If it’s the latter, they are content with a diminished role for the United States and are banking, after all this time, on sitting down with the Iranians.

The ramifications of repeated acts of weakness are significant, he told me. “Even if you are a friend of the United States, the incentive is to cut your own deal with Iran.” Without a strong U.S. presence on which they can rely, friends and foes will make self-interested calculations. In the case of foes, Bolton said that “they spend the first year or 18 months” sizing up the president and then, finding him weak, begin to exploit that weakness. He contends that is why, in conjunction with the realization that they may have a new president to deal with in a year, the Iranian mullahs have stepped up the pace of aggression (e.g., the assassination plot on the Saudi ambassador). Meanwhile, he warned, “You have a self-perpetuating cycle of downward [U.S.] influence” with a president whose focus has never been on foreign policy.

Bolton said he is heading to South Carolina for a Romney foreign policy speech on Hilton Head Island. Beyond that, he said, “I’ll do whatever they’d like me to.” Many conservatives hope that would include accepting a senior national security post in a Romney administration.