Age can be a mixed blessing in politics. On the one hand, older candidates are generally viewed as more experienced and qualified. But, older candidates can also have more trouble connecting with and mobilizing younger voters.
Much like Obama in the 2008 election, Rubio has been attacked for his lack of political experience. However, the young Florida senator has 15 years of elected-office experience under his belt, which is exactly the average for the 2016 candidates.
Cruz was the first person to officially announce his candidacy for president in March 2015. Nearly nine months later, Cruz is still holding steady in the race.
#16. Martin O'Malley
O'Malley is significantly younger than his two Democratic opponents, but he has had trouble connecting with young voters. He'll need to gain some serious momentum soon if he hopes to save his campaign.
The former Arkansas governor first ran for president in 2008, when he was 53 years old. Although he lost the GOP nomination to John McCain, Huckabee became a more nationally recognized figure in the process.
#11. Lindsey Graham
Graham has consistently been in the bottom of the polls — he has yet to graduate from the undercard debates — but he is showing no signs of slowing down his campaign.
After a confident performance in the first GOP undercard debate, Fiorina broke onto the main stage in subsequent debates. She'll need to convince voters that her business experience translates into politics.
If Bernie Sanders won the 2016 election, he would be the oldest president in U.S. history; a title currently held by Ronald Reagan. Sanders has no shortage of experience in politics (he has served as an elected official for over 34 years), but critics see his age as a potential liability in office.
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OAKLAND, CA - AUGUST 10: Independent presidential candidate U.S. Sen. Bernie Sanders (I-VT) takes a selfie with a nurse from the National Nurse United during a 'Brunch with Bernie' campaign rally at the National Nurses United offices on August 10, 2015 in Oakland, California. The National Nurses United members announced their endorsement for independent presedential candidate Sen. Bernie Sanders during a campaign stop before he heads to Los Angeles for a campaign rally in Los Angeles at the Memorial Sports Arena. (Photo by Justin Sullivan/Getty Images)
EDISON, NJ - AUGUST 30: A golf fan takes a 'selfie' with presidential candidate Donald Trump during the final round of The Barclays at Plainfield Country Club on August 30, 2015 in Edison, New Jersey. (Photo by Ross Kinnaird/Getty Images)
Scott Walker, governor of Wisconsin and 2016 Republican presidential candidate, right, takes a selfie photograph with an attendee during the Iowa State Fair in Des Moines, Iowa, U.S., on Monday, Aug. 17, 2015. Like most every other candidate in the historically crowded field, the Wisconsin governor's standing in state and national polls has been hurt by the summer surge of billionaire Donald Trump, the party's front-runner. Photographer: Daniel Acker/Bloomberg via Getty Images
ANAHEIM, CA - SEPTEMBER 09: Physician Tamara Hoover (C) takes a selfie with Republican presidential candidate Ben Carson cheer during a campaign rally at the Anaheim Convention Center September 9, 2015 in Anaheim, California. Carson's poll numbers have surged nationally and in the early voting state of Iowa following his performance in the first Republican debate on August 6 to the point where he now trails only frontrunner Donald Trump. (Photo by Kevork Djansezian/Getty Images)
Senator Bernie Sanders, an Independent from Vermont and 2016 U.S. presidential candidate, left, takes a 'selfie' photograph with an attendee during a town hall meeting in Davenport, Iowa, U.S., on Thursday, May 28, 2015. Sanders formally joined the 2016 Democratic presidential race this week, hoping to start 'a political revolution to transform our country economically, politically, socially and environmentally.' Photographer: Daniel Acker/Bloomberg via Getty Images
Ben Carson, 2016 Republican presidential candidate, stands for a selfie photograph with an attendee following a service at Maple Street Missionary Baptist Church in Des Moines, Iowa, U.S., on Sunday, Aug. 16, 2015. Carson will be speaking at the Iowa State Fair, which is expected to host 18 presidential candidates and runs until Aug. 23. Photographer: Daniel Acker/Bloomberg via Getty Images
DES MOINES, IA - APRIL 15: Democratic presidential hopeful and former Secretary of State Hillary Clinton (R) stops to take a selfie after meeting with members of the Iowa State legislature at the Iowa State Capital on April 15, 2015 in Des Moines, Iowa. Hillary Clinton continues to campaign throughout Iowa as she makes her second bid for President of the United States. (Photo by Justin Sullivan/Getty Images)
DES MOINES, IA - AUGUST 13: Democratic presidential hopeful and former Maryland Gov. Martin O'Malley (C) takes a selfie in front of the Butter Cow with his children Grace (L) and William (R) during the Iowa State Fair on August 13, 2015 in Des Moines, Iowa. Presidential candidates are addressing attendees at the Iowa State Fair on the Des Moines Register Soapbox stage. The State Fair runs through August 23. (Photo by Justin Sullivan/Getty Images)
NASHVILLE, TN - AUGUST 29: Republican presidential candidate Donald Trump poses for a photo with a woman speaks at the National Federation of Republican Assemblies (NFRA) Presidential Preference Convention at Rocketown on August 29, 2015 in Nashville, Tennessee. GOP front runner Donald Trump leads most polls in the race. (Photo by Jason Davis/Getty Images)
Donald Trump, president and chief executive of Trump Organization Inc. and 2016 Republican presidential candidate, stands for a selfie photograph after speaking during a rally at Grand River Center in Dubuque, Iowa, U.S., on Tuesday, Aug. 25, 2015. President Barack Obama's top business ambassador dismissed Trump's call for a wall along the Mexico border, saying the U.S. is focused instead on expanding business with one of its biggest trade partners. Photographer: Daniel Acker/Bloomberg via Getty Images
Ben Carson, 2016 Republican presidential candidate, center, is seen on the screen of a smartphone as he poses for a 'selfie' photograph with two attendees while touring the Iowa State Fair in Des Moines, Iowa, U.S., on Sunday, Aug. 16, 2015. In a Sunday interview with Fox News, Carson doubled down on his assertion that a speech given by President Barack Obama intended to sell the American public on his nuclear deal with Iran contained 'coded innuendos employing standard anti-Semitic themes.' Photographer: Daniel Acker/Bloomberg via Getty Images
DENVER, CO - AUGUST 4: Hillary Clinton takes a selfie with a supporter after delivering her speech on August 4, 2015 at La Rumba. Clinton, one of the presidential candidates trying to gain support for the Democratic nomination, held her first campaign event outside of early primary states in Colorado. (Photo By Brent Lewis/The Denver Post via Getty Images)
SPARTANBURG, SC - APRIL 3: Senator and GOP presidential candidate Ted Cruz takes a selfie with supporters following a town hall meeting at the Beacon Drive-in restaurant on April 3, 2015 in Spartanburg, South Carolina. The Beacon Drive-in, traditionally a popular venue for campaigning politicians, was Cruz's 2nd stop of the day in South Carolina. (Photo by Richard Ellis/Getty Images)
MIAMI, FL - SEPTEMBER 01: Republican presidential hopeful and former Florida Gov. Jeb Bush takes a selfie photo with a student as he attends a town hall style meeting at La Progresiva Presbyterian School on September 1, 2015 in Miami, Florida. Jeb continues to campaign for the Republican nomination. (Photo by Joe Raedle/Getty Images)
DES MOINES, IA - AUGUST 14: Republican presidential hopeful and former Florida Gov. Jeb Bush (C) takes a selfie with fairgoers at the Iowa Pork Tent during the Iowa State Fair on August 14, 2015 in Des Moines, Iowa. Presidential candidates are addressing attendees at the Iowa State Fair on the Des Moines Register Presidential Soapbox stage. The State Fair runs through August 23. (Photo by Justin Sullivan/Getty Images)
LEXINGTON, SC - JUNE 15: GOP presidential candidate, U.S. Sen. Rand Paul (R-KY) has a selfie taken with a supporter at the VFW Hall on June 15, 2015 in Lexington, South Carolina. Paul took questions and spoke against government intrusion into the lives of citizens. (Photo by Richard Ellis/Getty Images)
LAS VEGAS, NV - JULY 14: Photographer Victor 'The SnakeMannn' Wolder (L) takes a photo with Wisconsin Gov. Scott Walker at Red Rock Harley-Davidson on July 14, 2015 in Las Vegas, Nevada. Walker launched his campaign on Monday, joining 14 other Republican candidates for the 2016 presidential race. (Photo by Ethan Miller/Getty Images)
FLORISSANT, MO - JUNE 23: Democratic presidential candidate and former U.S. Secretary of State Hillary Clinton (R) takes a selfie with kids during a visit to a youth summer camp before speaking to supporters on June 23, 2015 at Christ the King United Church of Christ in Florissant, Missouri. Clinton's visit to the St. Louis suburb neighboring Ferguson, Missouri focused on racial issues. (Photo by Whitney Curtis/Getty Images)
Donald Trump, president and chief executive officer of Trump Organization Inc. and 2016 Republican presidential candidate, takes a selfie photograph with guests after an interview on Bloomberg Television's 'With All Due Respect' in the lobby of the Trump Tower in New York, U.S., on Wednesday, Aug. 26, 2015. Trump said that he agrees the carried interest tax 'loophole' should be eliminated and that it is 'tremendous burden' on country's finances. Photographer: Michael Nagle/Bloomberg via Getty Images