John R. Bolton, ambassador to the United Nations during the George W. Bush administration, told a crowd of more than 100 in Baltimore on Sunday that Mitt Romney is the only candidate on Tuesday’s primary ballot suitable to “sit at the big desk” and make the important decisions looming on U.S. foreign policy.

Bolton also expanded on his criticism of President Obama’s unguarded comments last week in South Korea to Russian President Dmitry Medvedev when Obama said he would have “more flexibility” to discuss missile defense after the November election.

“I was astounded by it,” Bolton said. “I’ve been in a lot of negotiations and you have candid conversations with the guy across the table, but I have never heard of a president saying ‘give me’ – ‘give me’ – some space until after the election, and then I can give you more of what you want.

President Obama was overheard on an open mike giving outgoing Russian President Medevev a candid political assessment of his ability to deal with relations between the United States and Russia, saying he would have more flexibility after the election.

Bolton’s lunchtime talk to a standing-room only crowd at a Kosher restaurant in the northern Baltimore suburb of Pikesville was the biggest event of the day for any GOP contender in Maryland.

The national focus on Tuesday may be on Wisconsin, and a potential momentum-halting loss for Rick Santorum. But the contest in Maryland is considered the first time since the 1976 that the outcome of the Old Line State’s primary could factor as heavily in the outcome of a GOP presidential nomination.

Bolton said Obama should have known not to make such a sensitive comment in a public room – especially abroad.

“My assumption is anything you say that doesn’t take place in a room behind closed doors is public because if you’re in a conference room with 20 countries, you can never be sure that somebody is not listening,” Bolton said. “If you have something that you think is really sensitive, you say ‘can we go over here,’ or ‘can I talk to you later?’

“It tells me Obama felt very comfortable sharing this idea with Medvedev.”

The former UN ambassador known for his hawkish views, also channeled former President Franklin D. Roosevelt, telling the crowd that the U.S. must address Iran — the rattlesnake in the Middle East — before it strikes.

“President Obama’s stance on Iran is extraordinarily weak. I don’t think he has any credibility,” Bolton said. “I think he’s calibrating the sanctions Congress passed last year based on political considerations and I don’t think it’s going to work and I think he knows it.”

Bolton also said the significance of expected Romney wins Tuesday in Maryland and the District should not be overlooked.

“Winning here in Maryland and in D.C. on Tuesday will mark another significant step to show that Romney is the only truly national candidate left,” Bolton said. “The sooner we get our act together, and everybody comes back into focus on the main event, the greater the likelihood we’ll win” the general election, Bolton said.