Jeb Bush speaks at the Republican presidential candidates debate in North Charleston, South Carolina, Jan. 14, 2016. Reuters

Presidential candidate and former Florida Gov. Jeb Bush isn't a Donald Trump fan. The billionaire isn’t serious about strong American foreign policy, Bush said, adding that even if he’s ahead in the polls, Trump has been talking trash without backing it up.

“We have to restore a traditional role in foreign policy and you can't do that by rambling along and saying that [Russian President Vladimir] Putin can take care of ISIS,” Bush said during an event at the Council on Foreign Relations in New York City on Tuesday, aimed at helping him rebuild his faltering campaign. “You can’t keep us safe by talking trash without backing it up with serious plans.”

But despite the tough talk, it's not at all clear that Bush’s clarion call for new American leadership abroad will differentiate him in a way that boosts his chances of winning the Republican nomination against candidates like Trump, according to political scientists and GOP strategists. Bush has branded himself as “the steady hand” and the adult in the room when it comes to foreign policy, but Republican primary voters right now aren’t interested in that sort of thing. To make a comeback, Bush will need to do one of two things: Show primary voters that opponents like Trump aren’t engaged in realistic foreign policy discussions, or start speaking in digestible soundbites like the popular New York businessman.

“The reason Trump is so popular is that he says the kind of things people say at the Keurig machine when they’re getting coffee in the morning,” Rich Galen, a Republican strategist unaffiliated with a presidential campaign said. In other words, people are more likely to say they want a president who will “ bomb the s--- out of ISIS ” like Trump has done, than one who talks about rebuilding international coalitions and partners in the Middle East, like Bush did Tuesday. But, Galen noted that the issues voters care about in the primary and general elections tend to contrast and can change quickly. Bush may still have time to make a splash in the Republican primary when voting starts in Iowa Feb. 1.

That chance to shine is quickly shrinking, though, and the competition for the more moderate conservative primary voters that Bush is trying to appeal to is getting more heated every day. While Bush was once talked about as the inevitable Republican nominee, he’s dropped in the polls noticeably since late July when Trump overtook him in national polls. Bush finds himself in fifth place with just 4.8 percent of the national vote in an average of polls compiled by Real Clear Politics. Trump, in first place, takes in 34.5 percent of the national vote.

With those poll ratings, some GOP leaders aren’t so convinced that there’s still a chance for Bush no matter what he does.

“I honestly don’t think there’s a lot in Jeb’s portfolio at this point that he gets to play out. The main trouble for Jeb is he’s become perceived as unelectable, perceived as a guy whose campaign is falling apart,” Rick Wilson, a Republican strategist who is unaffiliated with a campaign said. “There’s no particular distinction in Jeb on anything right now that matters to voters on foreign policy that could be decisive in the race.”

Unless voters take a look at Bush from a different perspective, Trump and Cruz are going to continue to look strong on foreign policy, regardless of how unrealistic they may be.

“Yes, it can seem weak if you’re surrounded by chest thumping and you don’t thump your chest. Maybe you seem weak, but when you get past the primaries it also seems real,” Matthew Baum, a professor of global communications at the Harvard Kennedy School of Government in Massachusetts said. “I’m trying not to be flippant about this, but in the land in which this Republican primary debate is occurring, [Bush] may seem a little weak. Back in the real world [Cruz’s and Trump’s] policies are fantasies. They’re never going to happen.”

RCP Poll Average for Republican Presidential Candidates | InsideGov

Bush listed a series of policy proposals in quick succession on Tuesday, criticizing President Barack Obama for allowing the U.S. military to shrink in power while letting international crises handle themselves and letting alliances with foreign partners deteriorate. The United States has seen shrinking economic activity, he said, and the country needs to reestablish its former glory while modernizing.

“We’re living in a 21st century world that has new threats, new challenges, new opportunities,” Bush said. “It’s important for us to, I think, reestablish the proper role of the United States in the world. The world has been torn asunder and our alliances have been tattered.”

“We need to make sure that there is a permanent source of security,” Bush added. “And, diplomacy needs to go hand in glove.”

But even those who showed up to hear Bush talk Tuesday said that while they appreciated Bush’s willingness to add his voice to complex conversations on foreign policy, they had little confidence that Bush would make a comeback. Bush may say that he's the more mature presidential candidate, but Trump is winning over voters with charisma that Bush doesn't seem to have — one audience member even joked they needed coffee before the "low-energy" Bush talk, a common Trump joke about Bush.

“I think his chances are very low. But this is a contribution to the collective conscious,” Barbara Kellerman, a professor of leadership at Harvard University in Massachusetts, said of Bush's talking points. Kellerman had come to Bush’s foreign policy event from Connecticut where she lives but didn’t expect to hear much she hadn’t heard before. She, like many others in the audience, wasn't planning on voting for Bush, although she said she was undecided about who would get her vote. “It's almost a relief to hear somebody talk about something like this in a campaign that is dominated by soundbites," she said.

Others showed up to simply try to understand what had happened to Bush’s once inevitable campaign. Trump’s rise is hard to understand, Sven Howles, who works at professional services firm KPMG in New York City, said.

“I’m here just to know what he has to say about the general campaign and why it’s different this year from other years,” Howles, a Democrat who would like to hear a more reasoned presidential debate, said. “I’d like to hear what’s his view on why this has happened.”

Bush, despite his probing rhetoric, didn't seem to have that answer.

"I’m the only guy confronting this because people are anxious about their future, they’ve latched onto the large personality on the stage but the reality is that he’s not a serious candidate,” Bush said. “And he’ll get wiped out in the general election."

He wrapped up his speech with a final nod at Trump's brazen debate skills, quipping, "I didn't insult anybody."