(Corrects day of the week to Tuesday, paragraph 17)

By Patrick Markey

BOGOTA, June 6 (Reuters) - Under pressure for a scandal at home, Colombian President Alvaro Uribe faces a tough task in Washington this week when he seeks to salvage a U.S. trade deal and secure a multibillion dollar anti-narcotics aid package.

On his second visit in five weeks, Uribe is struggling to reassure U.S. Democrats uneasy with the trade accord and working to redirect the anti-drug and military aid Colombia relies on to fight guerrillas and cocaine traffickers.

In a region where anti-U.S. leaders have increasing influence, Colombia has been a key Washington ally. It receives the largest sum of U.S. aid outside the Middle East, about $700 million a year in mostly military spending.

But Democrats controlling Congress are skittish over Colombia's rights record, union activist murders and a probe tying some of Uribe's allies to illegal paramilitaries accused of atrocities in the country's drug-fueled conflict.

"You have to admire Uribe's tenacity and determination," said Michael Shifter at the Inter-American Dialogue in Washington. "The truth is, the politics are very difficult. If the trade deal is approved, it will not happen soon."

Uribe and his ministers will meet on Thursday with congressional Democrats, including New York Rep. Charles Rangel and Michigan Rep. Sander Levin, who want to extend an Andean trade tariff while the accord is reviewed.

"Colombia has done everything and is up-to-date in the process to approve the accord," Trade Minister Luis Guillermo Plata said. "We want some kind of bridge so we are not left hanging."

Democrats are demanding more conditions on the Colombia accord to ensure Bogota investigates alleged government links to the paramilitaries and halts murders of union leaders.

With U.S. lawmakers caught up in the debate over Iraq war funding, Colombia's trade deal could slip off this year's congressional agenda, analysts said.

A frustrated Uribe recently warned Congress not to treat his government like a pariah, while his vice president said without a trade accord, Colombia may review its U.S. ties.

"The issue of a trade agreement with Colombia is still very much up in the air," Rep. Gregory Meeks, a New York Democrat, said in Bogota this week.

AID DEBATE BEGINS

Uribe has led a hard-line campaign to combat left-wing rebels and disarm illegal paramilitary gangs with the aid of billions of dollars in military and counter-narcotics assistance from Washington.

Violence has dropped sharply and foreign investment is flowing into the economy. But a probe into paramilitary links to politicians has led to the arrest of pro-Uribe lawmakers and a slew of investigations.

Uribe says that proves Colombia's justice system is working. He has also pushed for more investigations into labor union killings and for more funds for the judicial system.

Some Democrats have long questioned the priority given to the military component of Colombia's deal and whether the package's concentration on drug crop fumigation was effective in reducing the cocaine shipped to U.S. streets.

Colombia remains the world's largest producer of cocaine. The latest U.S. figures for 2006 detected around 8 percent more coca leaf used to make the drug than a year earlier or

In a sign Colombia is under more scrutiny, the House appropriations subcommittee on Tuesday cut its 2008 aid budget by 10 percent to $530 million.

The committee also reduced the military and narcotics component of the package from 76 percent to 55 percent, and bumped up the social and development part to 45 percent from 24 percent, a congressional aide said. Lawmakers must still approve those revisions.

"I think they are using the power of the purse to send a message that the composition of the package should change," said Cynthia Arnson at the Woodrow Wilson Center. (Additional reporting by Adriana Garcia in Washington)

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