21st Century Safety Net?

The Washington Post reports on a Congressional bill to expand something called the Trade Adjustment Assistance program:

As part of their campaign to soothe an anxious middle class, congressional Democrats are preparing legislation that would significantly expand federal aid to the most obvious victims of the global economy: workers whose jobs move offshore or are lost to foreign imports.

Under a Senate bill to be introduced today, computer programmers, call-center staffers and other service-sector workers who make up the vast majority of the nation's workforce would for the first time be eligible for a generous package of income, health and retraining benefits currently reserved for manufacturing workers who lose their jobs to international trade.

Democrats say the expansion of the Trade Adjustment Assistance (TAA) program would begin to reweave the social safety net for the 21st century, as advances permit more industries to take advantage of cheap foreign labor -- even for skilled, white-collar work. By providing special compensation to more of globalization's losers and retraining them for stable jobs at home, they say, an expanded program could begin to ease the resentment and insecurity arising from the new economy.

Greg Mankiw asks 2 questions that seem to me must be considered crucial in evaluating whether the proposal should be law or not:

1. Can you really tell whether worker is losing his job due to trade or due to other forces, such as technological change?

2. Is a worker who loses a job due to trade deserving of a more generous safety net than a worker who loses his job due to other forces, such as technological change?

I suggest the answer to both questions is NO.

So, I wonder which rent-seeking group supports this legislation? I suspect it is not the "anxious middle class."