GUATEMALA CITY (Reuters) - A former TV comedian with no experience in government is poised to win Guatemala's presidential election on Sunday after a corruption scandal toppled the country's last leader and fueled voter outrage with the political establishment.

Playing up his outsider status and promising clean government, 46-year-old Jimmy Morales has surged in polls since a probe into a multi-million dollar customs racket led to the resignation and arrest of President Otto Perez.

Voter surveys show Morales is primed to easily beat former first lady Sandra Torres, who also vows to tackle corruption but is seen by many voters as part of the old political order.

"If I have to pick, it will be Jimmy Morales," said Nelson Lemus, a 37-year-old driving instructor, offering rather faint praise for the self-proclaimed centrist. "At least we don't have anything that speaks against him yet."

Reaching out to voters with tales of his humble origins and jokes from a 14-year stint on a sketch comedy show, Morales has faced criticism over fanciful policy ideas, like tagging teachers with a GPS device to make sure they show up in class.

His manifesto runs to just six pages, giving few clues as to how he might govern, and his National Convergence Front (FCN) will have just 11 out of 158 seats in the next Congress.

"He has no program and no team," said Hugo Novales, a political analyst at Guatemalan think tank ASIES. "But discontent is so high that those issues aren't a priority for your average voter."

Just a few months ago, Morales was a rank outsider, but as probes by a U.N.-backed body targeting public sector corruption engulfed the government and the campaign of the election front-runner, the clean-cut comic surged into contention.

One investigation found that Perez and his vice president were at the heart of the customs scam known as La Linea. After being impeached, stripped of his presidential immunity and arrested last month, Perez is now behind bars awaiting trial.

Perez denies the allegations against him, but the scandal has sorely tested already shaky public trust in politicians.

Morales, voters hope, will offer a complete break from this.

His center-left opponent Torres, 60, has vowed to extend welfare programs that were once a hallmark of the presidency of Alvaro Colom, when she was first lady.

Critics say Torres, whose National Unity of Hope (UNE) party has traditionally fared well in poor rural areas, used her role as the head of a powerful welfare committee under Colom to make state handouts dependent on political loyalty.

Morales also has his detractors.

The former funny man has had to reassure voters his party is not too close to the military, which played an often brutal role in Guatemala's 1960-1996 civil war.

Some founders of his FCN, were, like Perez, members of the army, though Morales says the party's core is now civilian.

Others worry about the policy agenda of the onetime theology student, who has promised to hand out smartphones to kids and revive a territorial dispute with neighboring Belize.

The comedian beat Torres in a first round of voting on Sept. 6 in a field of 14 candidates but fell short of the 50 percent of votes needed to avoid a run-off.