By Adriana Barrera and Sofia Menchu

GUATEMALA CITY (Reuters) - Former first lady Sandra Torres won a clear victory in the first round of Guatemala's presidential election, results showed on Monday, but the center-left candidate faces a tough test to see off her nearest conservative rival in a direct runoff in August.

With votes tallied from 98% of polling stations, preliminary results from Sunday's election gave Torres 25.70% of the vote, followed by conservative Alejandro Giammattei with 13.92%, the electoral tribunal said.

Torres said on Monday she would work to forge alliances to win the runoff, which is due to be held on Aug. 11. The national vote was split between 19 contenders.

"The country needs unity: To unite the countryside with the city, to unite the workers with the business community, and also in civil society, in all sectors," she told reporters.

The next president faces the daunting task of curbing drug gang violence that has ravaged Guatemala and helped spur illegal immigration to the United States, souring relations with President Donald Trump, who has pledged to stem the flow of asylum-seekers across the southern border with Mexico.

The Trump administration on Monday cut hundreds of millions of dollars in aid to Guatemala, El Salvador and Honduras over the three countries' immigration policies.

The prospect of losing aid has caused alarm in Guatemala, where the legacy of its bloody 1960-1996 civil war still casts a long shadow over the country's checkered development.

Results from Guatemala's congressional election on Sunday suggested its next legislature would be divided. Torres' UNE party had won 18.1% of the vote on the national list with about 97% of returns counted. No other party managed even 10%.

Jose Carlos Sanabria, a political analyst from the ASIES think tank in Guatemala City, said whoever became president would struggle to craft a working majority. "I think it will be hard to move the legislative agenda," Sanabria said.

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Torres has for weeks led the race to succeed President Jimmy Morales, a conservative former television host whose term has been blighted by accusations of corruption.

She has pledged to send troops into the streets to fight drug gangs, and use welfare programs to tackle poverty.

But the former wife of ex-president Alvaro Colom also has high negative ratings, and faces a real test to win a direct runoff if conservative voters unite against her.

The third-placed contender, Edmond Mulet, is also a conservative. A former U.N. official, Mulet took 11.18% of the vote, and parties from the right of the political spectrum won more support overall than the left, the results showed.





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Results suggested many voters were unhappy about the choice of candidates on offer. More than 13% of votes cast were blank or spoiled ballots, the preliminary count showed.

President Morales, who is barred by law from seeking re-election, took office in 2016 vowing to end corruption after his predecessor was brought down by a probe led by the U.N.-backed International Commission against Impunity in Guatemala (CICIG).

Instead, Morales himself became a target of a CICIG probe into allegations of campaign finance wrongdoing and was subject to impeachment proceedings in 2017.

He survived the attempt to oust him, and then engaged in a bitter dispute with the CICIG before finally terminating its mandate, effective from September. The presidential candidate for his FCN party picked up just over 4% of the vote.

None of the top three contenders unequivocally backed the CICIG, with Torres saying she would consider holding a referendum on whether it should remain in Guatemala.

Sunday's election has been clouded by questions of legitimacy since two of the front-runners were forced out, including Thelma Aldana, a former attorney general who tried to impeach Morales with the CICIG. Prosecutors accused Aldana of corruption, leading to her exclusion last month.





(Additional reporting by Daniel Flynn; Writing by Dave Graham; Editing by Darren Schuettler, Paul Simao and Sonya Hepinstall)