Two near-opposite pieces of immigration legislation were introduced last week, revealing the sharp contours of the debate reformers will have to deal with if they hope to pass comprehensive immigration legislation.

Rep. Duncan Hunter (R-Calif.) introduced legislation to speed up completion of the Mexico-U.S. border fence, mandating an additional 350 miles of fencing within a year. It's often reported that over 600 miles of the originally-required 700 miles of fencing have been completed. That's true, but half of the current fence is designed to stop vehicles, rather than pedestrians. Conservatives contend vehicle fencing--including bollards or poles set several feet apart--do not stop illegal immigrants on foot.

"That figure is misleading because over half the infrastructure along the border consists of vehicle barriers, which do not limit illegal foot traffic," said Joe Kasper, a spokesman for Hunter.

Besides mandating additional pedestrian fence construction, Hunter's bill would increase sentencing for weapons smuggling, punish so-called "sanctuary cities," and require all employers to electronically verify the immigration status of employees.

Meanwhile, Rep. Raul Grijalva (D-Ariz.) has introduced a bill to SLOW construction of the border fence, citing concerns over environmental damage and tribal sovereignty. The bill would require more consultation with state and local governments, public notification, and stricter enforcement of environmental regulations.

"Current policy has driven crossing activity to remote isolated areas along the border which, in Southern Arizona, represent significant public and tribal lands," said Grijalva. "Many of these lands have suffered extensive environmental degradation as a result of unauthorized activity and border security efforts."

Grijalva's concerns mirror the position Obama took during the campaign.

"I think that the key is to consult with local communities, whether it's on the commercial interests or the environmental stakes of creating any kind of barrier," Obama said at a debate in Austin.

Thus far, the administration is moving forward with construction. Homeland Security Secretary Janet Napolitano, a critic of the fence as governor of Arizona, has committed to finishing the 670 miles mandated by Congress in 2006.