They did not. What is the source for your assertion? They did sign a 700 mile fence bill authorization, which had some funding associated with it. This bill provided cover for the Dems and should not have been passed. Even Hillary voted for it.
Last-minute bill changes funding for border fence
WASHINGTON - No sooner did Congress authorize construction of a 700-mile fence on the U.S.-Mexico border last week than lawmakers rushed to approve separate legislation that ensures it will never be built, at least not as advertised, according to Republican lawmakers and immigration experts.
GOP leaders have singled out the fence as one of the primary accomplishments of the recently completed session. Many lawmakers plan to highlight their $1.2 billion down payment on its construction as they campaign in the weeks before the midterm elections.
But shortly before recessing late Friday, the House and Senate gave the Bush administration leeway to distribute the money to a combination of projects -- not just the physical barrier along the southern border. The funds may also be spent on roads, technology and "tactical infrastructure" to support the Homeland Security Department's preferred option of a "virtual fence."
The loopholes leave the Bush administration with authority to decide where, when and how long a fence will be built, except for small stretches east of San Diego and in western Arizona. Homeland Security officials have proposed a fence half as long, lawmakers said.
This case reflects political calculations by GOP strategists that voters do not mind the details, and that key players -- including the administration, local leaders and the Mexican government - oppose a fence-only approach, analysts said.