Last week, it appeared all but certain that Los Angeles area Congressman Xavier Becerra would be Barack Obama’s US Trade Representative. And when it became clear that Obama had, in fact, extended the offer to Becerra, that the deal was all but set in stone.

But something curious happened: Becerra backed out and declined the offer.

The US Trade Representative is a Cabinet-level position. While there is no “US Department of Trade”- which would make the USTR a “Secretary” by official title, but it bestows upon the appointee all of the diplomatic rights and privileges assigned to the other members of the Cabinet.

In the hierarchy of Washington government, Cabinet level positions are pretty high on the list. That’s why sitting governors and senators (like Colorado Senator Ken Salazar, who was appointed Secretary of Energy, or New Mexico Governor Bill Richardson, who was appointed Secretary of Commerce) will happily leave their jobs to take on executive positions. Because there are so few of them, Senators and Governors come next on the list, with Senators usually ranking a bit higher than governors (though that’s not always a rule. While many governors will run for the Senate after their terms, you’ll see the reverse in certain big states, like when Pete Wilson left the Senate in the early 1990s to become Governor of California).

But Congressmen rank pretty low on the totem poll. So its hard to see how Becerra, a relatively young 50 year old Stanford-educated Latino Democrat who has 15 years of Capitol Hill service under his belt, would turn it down. Becerra released a statement saying that he believed he could accomplish more as a Congressman. But apparently he forgot that there are 434 others out there who have the exact same title he does.

Becerra holds no party leadership post. He doesn’t even hold any chairmanships. In fact, he doesn’t even hold any chairmanships of subcommittees. (To be fair, he is on the Ways and Means Committee, which is one of the more powerful groups on the House floor). And while he might be in line for a chairmanship or leadership job in the next few years, his path to becoming Whip or Speaker would likely be a long one.

Moreover, Becerra’s name isn’t the first that comes to mind in terms of California’s two Senate seats. Besides, neither will likely be opening up in the near future. Barbara Boxer has already declared her intention to run for reelection in two years. Diane Feinstein hinted at the possibility of running for governor in 2010, but that is highly improbable. What it does suggest, however, is that she’s not planning on retiring any time soon.

Becerra’s primary reasoning is that he doesn’t believe that trade will be a major focus of the Obama Administration’s first term. But in reality, trade couldn’t be more important. The free-trade policies pushed during the last 16 years have depleted the American labor force, outsourcing tens of thousands jobs that formerly belonged to American workers. Unemployment is now skyrocketing. New trade policies designed to keep jobs in the US are going to be vital to restoring some semblance of order to the shaky economy.

What’s more is that the position is one that typically affords a strong opportunity for further growth. The previous USTR under President Bush was Rob Portman, who was subsequently promoted to director of Office of Management and Budget, another Cabinet-level position and the overseer of the largest segment of the Executive Office.

It’s hard to see how Becerra didn’t make a huge mistake. Because Obama probably won’t ask twice. And that means for at least the next four, and perhaps the next eight years, Becerra is going to stay right where he is.