They’re 44. They’re first-term U.S. Senators. Beltway freshmen.

They both got to Congress with the emphatic support of conservatives, the fervent support of tea party groups.

And both men – who also share Cuban heritage – want to be the next president of the United States.

But only one of them, Marco Rubio of Florida, is told that it’s too soon, that he’s too young, that he must gain more experience in his job to better learn the ways of national governing and politics.

He hears it all the time – in media interviews, in the GOP debates. He’s seen as too hungry, overly ambitious, impatient, selfish.

Rubio was prepared for the criticism, addressing it head-on in the speech he delivered when he announced he was running for president in Miami’s iconic Freedom Tower.

“I have heard some suggest that I should step aside and wait my turn,” he said before about 1,000 supporters. “But I cannot. Because I believe our very identity as an exceptional nation is at stake, and I can make a difference as president.”

Why is Rubio treated differently than Cruz, despite their same age and lack of experience in Washington, D.C.?

“Most of the Republican presidential candidates, from Ronald Reagan and George H.W. Bush to John McCain and Mitt Romney have generally been people in their 50s and 60s or older,” Cal Jillson, political science professor at Southern Methodist University in Dallas, told Fox News Latino. “Here’s Marco Rubio, a fresh-faced kid who’s seen as trying to jump into the race and relatively inexperienced. He’s got more of a baby face than Ted Cruz, who's got a ‘quiet assassin’ type [of face].”

Most voters do not study the details of policy positions of presidential candidates, and debates tend to veer off into sound bytes and demeanor, experts say. So gut instincts end up playing a big part in how the public feels about a candidate.

“People look for clues and cues to tell them whether a candidate is dependable, experienced, whether they could understand you.,” Jillson said. “Middle-aged and older voters tend to equate a few wrinkles with experience. They look to see who has the seasoning to be president. Some people think Rubio is not seasoned enough, too young” to handle someone like Vladimir Putin.

The theme of Rubio as too young was also embraced by political veterans who deemed it presumptuous of him to enter the presidential race when it was expected that his longtime friend and mentor, former Florida Gov. Jeb Bush, would run for the Oval Office.

"The way Rubio and Cruz are presented in the media reflects their relationship to the Republican national party,” said Edward Erikson, a political consultant, recalling how many Democratic party leaders did not react approvingly at first to Senate freshman Barack Obama’s decision to run for the nomination that had been seen as belonging to Hillary Clinton.

“Barack Obama was a rising star in the Democratic Party in 2008, just like Marco Rubio is a rising star in the Republican Party today,” Erikson said. “In both instances, these candidates bucked party leadership by cutting in line for the White House and competing against their party's heir apparent. In both instances, the candidates are tagged as ‘too young’ and ‘too inexperienced.’ This is a response to not following the established order and hierarchy.”

Ted Cruz is treated different, Erikson noted, because he is “a party gadfly.”

“Even though both he and Rubio came to the Senate as insurgent tea party candidates, Ted Cruz embraced his role as an outsider,” Erikson said, “and he used his position as an outsider to antagonize the leadership and build his national profile, while Rubio embraced the national party.”

And the GOP responded by giving Rubio one of its most coveted prizes – he was selected to give the official Republican response to President Obama’s 2013 State of the Union address. The plum job is seen as a way for the party to give maximum exposure to its rising stars.

But, as Erikson noted, the GOP’s blessings come with expectations of loyalty, and of following protocol.

Longtime Rubio aides conceded as much shortly after his announcement earlier this year, regardless of whether Bush also was leaning toward entering the race.

Early on, the D.C. establishment made calls for him to step aside for Bush, and since then Rubio has made the establishment GOP a target during his campaign.

Alex Conant, a Rubio campaign spokesman, said after the senator launched his campaign that establishment Republicans also had pressured Rubio to hold off running for the Senate in 2010.

“The establishment again told Marco to wait his turn earlier this year, but he is running for president because he believes America needs new leadership now,” Conant told reporters.

And Rubio has since echoed that idea. “In the latest Republican presidential debate, one of the moderators actually asked me if I should ‘slow down.’ That's exactly what the establishment has been telling me for years. That I should 'wait my turn.' Wait for what? This country is running out of time.”

“Millions of people are living paycheck to paycheck at the same time they're working as hard as they ever have, because everything costs more,” Rubio said. “They have not had a real raise in decades. Small businesses are struggling: more businesses are closing than opening. We live in a world that's out of control, with a president who's weakening our military and doubling down on a failed foreign policy while our adversaries continue to grow stronger.”

“The time to act is now, the time to turn the page is now,” Rubio said. “If we don't act now, we'll be the first generation that leaves our children worse off than ourselves.”

In the GOP field, Jillson said, Bush and Ohio Gov. John Kasich, both 62, have much more robust governing records than either Cruz or Rubio.

“They’ve had real accomplishments, they are much more experienced but they meander through their talking points,” Jillson said. “If they can’t deliver their point, voters who are paying much attention will wonder if they know what they’re talking about.”

Rubio and Cruz, he noted, are both superb debaters.

“They’re very articulate in very different ways,” he said. “They can reel off several sentences and sound coherent and sensible.”

For many Republican voters, age and experience are overrated. Rich Pedersen, a GOP activist in New Jersey, noted that some of the best leaders in history were young when they dared to vie for posts that were considered beyond them.

“Wasn’t John Kennedy young also and proved to be a good president?” Pedersen asked. “In my 76 years on this earth, I have found that age alone does not give a person the ability to solve problems and make the right decisions, nor be a great president.” 

He added, “Experience does help, but it is not necessary if an executive surrounds himself with experienced, intelligent employees or consultants.”

“Both Rubio and Cruz sound intelligent, but then so did Obama,” Pedersen went on. “Both Rubio and Cruz have demonstrated to me that they have a good knowledge of our country's problems and have solutions. Jimmy Carter told us what our problems were, but, as history has proven, he had no solutions.”

Pederson went on to say, “As for me, I'd vote for someone with a brain and ability. Look at the many senators and congressmen who have been in Washington for years and have contributed nothing.”

While Cruz aims to solidify his popularity with the right wing of the GOP, Rubio has been trying to walk the delicate line between the conservative and establishment factions.

He backed off from some unpopular positions, such as backing a path to legal status for undocumented immigrants, which drew the ire of many conservatives. Now he says he favors a piecemeal approach to immigration reform that first secures the borders.

“Marco Rubio is angling to be the consensus candidate,” Jillson said. “He’s for the traditional business community, which is a part of the party that wants you to wait your turn.”

“Cruz is at war with the traditional, business-friendly wing of the party,” he said. “He’s looking to be the favorite of the tea party, populist wing of the party – which wants a warrior, a guy who has his sword drawn.”

Cruz received praise after the last GOP debate, and he's impressed many with his fundraising prowess and his well-run campaign.

Some in the party now are seeing Rubio as their strongest candidate. After his performance in the third GOP debate – he’s been strong in all of them – and Jeb Bush’s stammering, some of which occurred after failed attempts to tear down Rubio, more of the establishment is lining up behind him. 

A major GOP donor, the influential billionaire Paul Singer, officially gave his support to Rubio this weekend. That important nod is expected to generate more donors flocking to the senator's cause.

“Just as Obama electrified the Democratic base in 2008, Marco Rubio has the potential to do the same for the Republicans,” Erikson said.

Other political observers say they take exception to the focus on age and looks when looking at who should be at the helm of the most powerful nation on Earth.

"Voto Latino has seen first-hand the power of young, vibrant leaders,” said Maria Teresa Kumar, the president and CEO of that get-out-the-vote group. “In cultivating Latino leaders, we have learned not to eliminate ideas or push leaders aside based on their youth.”

“The age of Sen. Rubio versus the age of Sen. Cruz should not be up for debate, and ageism of any sort should not be tolerated," Kumar said. "Rather, the focus should be on their leadership and their ability to move our country forward."