A new chapter in Argentina

Argentine Vice President Julio Cobos handed his own government its biggest defeat yet.

There's no two ways about it.

Argentina opened a new political chapter this morning when the country's Senate defeated a grain export tax hike President Cristina Fernandez de Kirchner had implemented in March, sparking four months of fierce protests by farmers.

The once-invincible Kirchners, which means the president and her husband, ex-Pres Nestor Kirchner, who only in October were seen as the saviors of this 40 million-person country, are now damaged goods. They've suffered their biggest defeat since taking power seven years ago.

The silence from the Casa Rosada, the country's presidential palace, today has been more telling than any comment.

The problem is the Kirchners bet so heavily on not backing down on the farm export tax hike on soybeans and other grains, which would bring in about $400 million in revenue this year. As a result, anything but total victory was a defeat.

By my count, they've held five mass rallies in Buenos Aires to support their side in the fight, and called farmers everything from coup plotters to ungrateful aristocrats.

Well, the Kirchners didn't just get a less-than-total victory but a bona fide defeat this morning, and what's especially stung is how it all went down.

With the Senate tied 36-36, Vice President Julio Cobos became the tiebreaker and amazingly voted against the farm tax, breaking with his government and throwing his political future in question.

As the dust settles, there are lots of questions.

First, what will happen to Cobos? He says he won't resign, but it's hard to imagine the Kirchners, who brook no dissent, will keep him on board after he handed them an embarassing setback.

What will happen to the farm taxes? The president sent the tax, which she implemented by decree, for Congressional approval only when public protests forced her hand.

Now, the bill goes back to the Chamber of Deputies where it'll have to be modified or shelved. Maybe the president will actually give some significant ground and hammer out with the opposition a version of the tax that's palatable to all sides.

Which leads to the biggest question: Will this humiliating defeat mark a new approach by the Kirchners?

They're famous for their prickliness, and they've unleashed fierce rhetoric against the farmers during the farm fight, alienating many Argentines.

The President is scheduled to speak later today for the first time since the Senate defeat. She has a chance to set a new tone.