ANALYSIS-Afghan vote: high noon for Karzai -- and Obama

(For more on Afghanistan, click on [ID:nAFPAK])

* Poll predicts election will go to second round

* Corruption remains key issue

* Country embraces campaigning with enthusiasm

By Peter Graff

KABUL, Aug 12 (Reuters) - When Afghans defy Taliban threats of bloodshed to stage an election on Aug. 20, their charming but care-worn president Hamid Karzai will not be the only leader with his future on the line.

Thousands of miles away, Barack Obama, who has wagered U.S. foreign policy on a rapid and overwhelming military escalation in Afghanistan to defeat the Taliban, has almost as much at stake.

Whoever wins, holding a successful election with a result that Afghans accept is crucial not just for Afghanistan, but also for Obama's revamped strategy to defeat the insurgents, the biggest foreign policy gamble of his own young U.S. presidency.

Karzai is still favourite to win, either with a first-round majority or in a run-off six weeks later, but he no longer wears the air of certain triumph he carried into Afghanistan's euphoric first democratic election five years ago.

This time, he faces two stronger foes -- one at the ballot box and one on the battlefield.

Karzai's main challenger, urbane former Foreign Minister Abdullah Abdullah, whose strength as a candidate has surprised Western diplomats, aims to win enough votes to force a run-off, while Taliban fighters, fiercer than at any time since they were driven from power eight years ago, want to cause enough bloodshed to prevent the election from taking place at all.

POLL PREDICTS SECOND ROUND

Western media sometimes describe Karzai as unpopular -- an easy assumption to make when you listen to Afghans complain about the rampant corruption, incompetence and nepotism in his government -- but although they often bemoan the parlous state of the country, polls clearly show most like their leader.

A U.S.-funded survey this week found two thirds of Afghans had a favourable opinion of him, with just 16 percent having an unfavourable view. But it also predicted Karzai would win a disappointing 45 percent of the vote and face a second round.

Despite the worsening war in the south and east, most of Afghanistan is at peace, its economy growing and its desperate poverty easing, if slowly for a country that has absorbed tens of billions of dollars in international aid.

A master coalition-builder, Karzai has won a formidable line-up of endorsements from regional bosses, many of whom may be expecting jobs in a future government to the alarm of Western diplomats keen to keep ex-guerrilla chiefs from carving up power.

But Abdullah, who emerged from a northern anti-Taliban alliance with roots in the ethnic-Tajik minority, has shown signs of winning support beyond that narrow base. The poll shows him easily placing second with 25 percent of votes.

If he forces a second round, Abdullah could unite the opposition to mount a stronger challenge, although his northern roots may still make it difficult for the former eye doctor to win enough southern support to become president.

TARGETING PURPLE FINGERS?

Staging a poll would be hard enough without the Taliban's threats in a country where barely a third of the population can read and ballot boxes have to be hauled over mountains by donkey.

Militants have broadcast threats by radio and spread leaflets, raising fears that voters' purple indelible ink-stained fingers -- once a jubilant sign -- could mark them for reprisals.

The United Nations said has says that threats and violence have already disrupted election preparations and sharply curtailed public campaigning in insurgent areas, and could prevent many Afghans from reaching the polls on election day.

Even if violence does not wreck the poll, it could make it more difficult to prevent fraud, and raise the odds of a run-off by suppressing turnout in southern areas that support Karzai.

The Obama administration's response to the worst violence of the eight-year-old war has been a forceful U.S. military escalation, aimed at tipping the balance.

About 30,000 additional U.S. troops have already arrived in Afghanistan this year, pushing the size of the Western force above 100,000 for the first time, including 62,000 Americans. More foreign troops have died in Afghanistan since March than in the entire period from 2001-2004.

Outside battle zones, ordinary Afghans seem to be enjoying the campaign season, which has seen their cities festooned with bright campaign posters and candidates pass out free meals.

The talk was all politics at the Faryab restaurant in downtown Kabul this week, where men reclined on rugs, scooping up fistfuls of rice and roast lamb from shiny metal trays.

"I'm voting for Karzai. These people, their pockets are already full. If we vote for anybody new, they will come with empty pockets, and until they fill their pockets, they will make all our lives miserable," said 33-year-old mechanic Mohammad Abbas, sparking knowing laughter from the room.