Updated: 6:04 p.m.

Sen. Robert Menendez (D-N.J.) introduced comprehensive immigration reform legislation Wednesday night — just hours before Senators left town to campaign for the midterms.

Menendez, a Cuban-American, pledged earlier this month to introduce a bill before the year’s end, although he conceded that it will only serve as a vehicle for moving forward on the issue in the next Congress. Although some Democrats had talked about addressing immigration reform in the 111th Congress, they didn’t get far: Most Members said they didn’t have the appetite to tackle another massive legislative overhaul.

Immigration reform advocates hailed Menendez’s move as progress on an issue that saw no action during this Congress.

“We commend Sen. Menendez for his strong leadership, and we look forward to working with him and others on this legislation,” said Ali Noorani, chair of the Reform Immigration for America Campaign. “It is a serious proposal that contains many of the common-sense ideas we have espoused for years.”

Menendez’s bill includes a number of controversial provisions, including a pathway to legalization for undocumented immigrants and the Uniting American Families Act, which would allow same-sex partners of permanent residents to qualify for a visa.

Rachel Tiven, executive director of the Immigration Equality Action Fund, praised the legislation as “welcome news not just for lesbian and gay Americans, but also their extended families, their communities and our country.”

A senior Senate Republican aide dismissed the bill’s introduction as a political exercise but warned Democrats against using the lame-duck session to pass controversial legislation like Menendez’s bill. Senate Democratic leaders have yet to signal whether immigration reform could come up after the election.

“I’d bet that most voters would have preferred Democrats spend the waning days of this Congress addressing the issues they care the most about, jobs and the economy, instead of trying to curry favors for their special interest groups,” the aide said. “Their election chances and the country would be better off if they would have acted to stop the upcoming tax hike on every American instead of playing politics.”

President Barack Obama said in a statement Thursday that he was glad that Menendez had introduced the bill and that he looked forward to reading it.

“The status quo is simply unacceptable for both our economy and our security,” he said. “Comprehensive immigration reform would provide lasting and dedicated resources for our border security, while restoring accountability and responsibility to the broken system.”