By his own admission, US presidential contender Marco Rubio comes from humble beginnings. But with the Florida senator joining the fray of Republican candidates vying for the 2016 nomination, his grit and determination will be one of his main weapons to counter leading contender Jeb Bush, the former Florida governor.

While the two candidates are both representing the same state and fighting for the same party nomination, they grew up on starkly opposite ends of the economic spectrum.

Rubio's mother was a maid, his father was a bartender and both were poor immigrants from Cuba. Rubio had to take out student loans to pay for college and finally paid them off just a couple of years back.

In sharp contrast, Jeb Bush was born into privilege, and both father and brother are former US presidents in one of the country's most powerful political dynasties.

"Rubio's background presents a clear contrast with Jeb Bush, who grew up with greater privilege," Brookings Institution's senior fellow Darrell West told Xinhua.

"I would expect Rubio to use his own personal story to his advantage and argue that he is more connected with the average person. That could help in certain states," he added.

In Rubio's speech last week announcing his candidacy, he told a live audience, "Both of my parents were born to poor families ... So in 1956 they came here." He said that while his parents never made it big, they were successful. "Two immigrants with little money or education found stable jobs, owned a home, retired with security and gave all four of their children a life far better than their own," he said.

Indeed, Americans love an underdog, and Rubio's story of self- made success resonates with many voters.

"The most compelling aspect of Rubio is his personal story. His message of climbing up from the bottom is a vintage American story. It is what people like about the country, that people of modest means can work hard and better themselves. That definitely will resonate with ordinary voters," West said.

But presidential campaigns are expensive, and Bush has an advantage in that area, as he can leverage his powerful family's connections to fund his presidential run.

Nevertheless, a few wealthy donors have come out to publicly support Rubio, saying he won't have trouble raising money, although that remains to be seen as his campaign progresses.

Bush has been a mentor to Rubio, as Rubio is a Florida senator and Bush a former governor of that state, and the two have so far been civil in public, with neither attacking the other as they both aim to grab Republican Party's nomination.

But the situation will soon change, and then sparks will fly between the two candidates.

Bush, when he was governor of Florida from 1999 to 2007, was viewed as more conservative than Rubio, and that may be something that his team can exploit as it aims to boost Republican voters' support in the primaries.

Already, Rubio has shown himself to be somewhat liberal leaning in some ways, such as on the issue of what determines people's sexual preference, saying Sunday on CBS' Face the Nation that he believes people do not choose their own sexual identity, but rather they are born with it.

Still, he toes the party's main line on equal marriage, which he said he opposes. Equal marriage has been a hot media topic in recent years, although it will not be one of the main concerns for most Americans in the run-up to the 2016 elections.

The author is a writer with the Xinhua News Agency. The article first appeared in Xinhua. opinion@globaltimes.com.cn