By Helen Murphy and Luis Jaime Acosta
BOGOTA (Reuters) - As a young business student at the University of Kansas, Colombia's President Juan Manuel Santos spent many a late night playing low-stakes poker and then invested his early winnings in shares of a pizza company.
"It was just nickel and dime stuff, but he was the man to beat. He was really good and knew how to bluff to win," said old university pal Phil Miller, recalling how Santos' steely face would break into a grin as he revealed a winning hand.
Four decades later and still known as an accomplished card player, Santos will need to muster all his cunning if he wants to clinch another term at the next presidential election in May.
With his approval ratings among the lowest recorded for a sitting president - a dismal 21 percent - after a series of labor disputes and slow-moving peace talks with Marxist rebels, some are asking if the deck is finally stacked against him.
But Santos, who faces a November deadline to decide whether he will run, has no obvious strong rival and may still have ace cards to play, especially if he reaches a deal with guerrilla leaders of the Revolutionary Armed Forces of Colombia, or FARC.
"If Santos wants to run again he will win. He knows how to manage things and has political support as well as backing from many Colombians," said Augusto Posada, a ruling party lawmaker.
"He will recover from this," Posada told Reuters, referring to the president's recent travails and slide in the polls.
A conservative U.S. ally from one of Colombia's most influential families, Santos enjoyed an approval rating of 76 percent shortly after taking office in 2010.
Now that his numbers have fallen, he is gambling that the peace talks will end 50 years of war with the FARC. That means his re-election chances - and his legacy - could now lie in the hands of three dozen rebel negotiators at the talks in Cuba.
The economy is showing steady growth, so if he can pull off a deal that ends the war and is palatable to Colombians, Santos is almost guaranteed a second term, even though many voters say he is out of touch with their problems
"He's not one of us, he's a rich kid from Bogota, but he's doing his best to change things. Ending the war would be a big deal and then I'd be willing to give him another shot," said milk farmer Eberto Castro, 52, on a bus outside Bogota.
After 10 months of negotiations in Havana, Santos' center-right government has yet to show much progress with the FARC, only reaching partial agreement on one of five agenda points.
Still, any quickening of the pace or signs that a final deal is in sight could be the winning hand Santos needs, especially if he is also able to start talks with Colombia's second-largest rebel group, the National Liberation Army, or ELN.
It is not enough, however, just to sign a peace deal.
Colombians are desperate to see an end to the fighting that since 1964 has claimed more than 200,000 lives - mostly civilians - but many do not want rebel leaders to have a free entry into civilian life, or seats in Congress, without first paying for their crimes.
Some critics, led by former president Alvaro Uribe, accuse the 62-year-old Santos of offering too many concessions to the rebels in order to win a place in history as the man who brought peace to Colombia.
Santos argues his opponents have no clue what is being discussed in the secret negotiations.
Responsible for operations that killed senior FARC leaders both as defense minister under Uribe and then as president, Santos insists there will be no impunity, but also says it is unrealistic to probe 50 years of war crimes.
Many expected Santos to defend big business when he took office, but he made cutting unemployment and aiding the poor a priority. He returned land stolen during the war, gave free homes to the most impoverished and offered subsidies to coffee and cacao growers when they protested earlier this year.
Those policies may have opened the floodgates to more demands for government handouts, with potato farmers, teachers and truckers all seeking improved conditions in recent protests.
Some opposition politicians say he must be far more radical if he wants to help the nation's struggling agriculture sector, like scrapping or renegotiating free trade agreements with the United States and Europe.
"The president has hinted he wants to run again, but if there is no policy change, those aspirations will crash against social discontent," said lawmaker Ivan Cepeda, whose leftist Polo Democratico party will likely run its own candidate in next year's presidential race.
Even with Santos' problems, though, it is tough to unseat an incumbent once the presidential campaign kicks in. Without a strong candidate, the opposition may struggle should he decide to run again.
Supporters say Santos' poor approval ratings may be artificially low because the latest poll was conducted at the worst point of nationwide farmers' protests that turned violent last month.
They point out that his popularity has seesawed throughout his presidency and that he has repeatedly bounced back. The killing of top FARC leader Mono Jojoy and the revelation he would seek peace with the Marxist group both came after his popularity had weakened.
In the last few weeks, he boosted his image as a tough leader by sending troops to quell violent protests in Bogota. And even Uribe applauded Santos' pledge to defend Colombia's sovereignty in a long-running dispute with Nicaragua over maritime frontiers.
Although Santos has hinted he will run again, he has not said for sure.
That could open the door for former rival-turned-collaborator German Vargas Lleras, who ran against Santos in 2010 and then joined his government as housing minister. He is thought to be on the sidelines waiting for the decision.
Should the feisty but popular Vargas Lleras turn against Santos and go it alone, he could present a major challenge to the president.
Uribe also remains a threat. While no longer the political king-maker that helped usher Santos into office before turning against him, Uribe's constant stream of criticism has chipped away at the president's support and put him on the defensive. He has been grooming his own candidates for next year.
Colombia's political left could also be in a better position for the next election than in recent races, gaining strength from labor protests that drew tens of thousands of Colombians to support farmers and state workers. Antonio Navarro Wolff, a former M-19 guerrilla leader, could be a viable candidate if he chooses to run.
Even as his rivals acknowledge Santos' approval ratings could rise again, they believe he is vulnerable.
"Santos played the Nicaragua card almost immediately and that will help, so did ending the farm protests. The other card would be a significant advance in peace talks," said Navarro Wolff. "But there's a big opportunity for a different candidate now."
(Additional reporting by Carlos Vargas; Editing by Kieran Murray and Vicki Allen)