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 opinion 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 set to easily win Sunday's run-off vote against former first lady Sandra Torres, who also vows to tackle corruption but is seen by many voters as part of the old political order.

As polling stations opened, many voters said they saw in the comedian an opportunity for a fresh start, and an end to the tainted political dealings that sparked nationwide protests and the eventual ouster of Mr Perez last month.

"We're tired of Guatemala's old-style politics ... the wholesale robbery of Guatemala," said 47-year-old small business owner Alejandro Cruz, after casting his vote in Guatemala City. "I voted for Jimmy Morales. I do think he will be victorious, and that today will be a historic day."

Connecting with voters with tales of his humble origins and jokes from a 14-year stint on a sketch comedy show, Mr 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, Mr 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 Mr 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, Mr Perez is now behind bars awaiting trial.

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