Washington - Launching the Senate Caucus to End Human Trafficking Wednesday, Sens. Richard Blumenthal, D-Conn., and Rob Portman, R-Ohio, joined forces across the political aisle to address a cause for which Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., has long been fighting: an end to human trafficking.

At the same time, Blumenthal suggested his bill, rather than Leahy's, has a better chance of passing before the end of the current Congress.

Blumenthal and Portman last March introduced legislation that seeks to end human trafficking by government contractors.

"Human trafficking is modern day slavery," said Blumenthal, who was joined at a press conference by actress/singer Jada Pinkett Smith, founder of the organization "Don't Sell Bodies."

While human trafficking by government contractors generally occurs abroad, "this problem has a dimension at home," Blumenthal said. "Out of all the cases of human trafficking the Department of Justice dealt with between 2008 until 2010, 83 percent of them involved U.S. citizens. ... It is an American problem as much as it is an international problem."

Leahy has sponsored a broader measure: the reauthorization of the Trafficking Victims Protection Act, which he has made a top priority in the session that convened this week.

The law was first enacted in 2000 and has been reauthorized three times since, although the latest reauthorization expired 14 months ago. While renewing the measure has the support of 52 senators, including 14 Republicans, the Senate has yet to vote on it.

Although Blumenthal is among the co-sponsors of Leahy's legislation, which he termed "very important," he noted: "Senator Leahy's bill is broader. It imposes penalties for human trafficking generally; it provides more funds for state and local programs to end human trafficking."

By comparison, "the bill to end human trafficking in government contracting provides penalties for government contractors, principally abroad, who involve human trafficking to provide labor for their projects," Blumenthal explained in an interview following the press conference. "Contractors, who are working, for example, on some kind of construction in a base in Afghanistan may use slave labor to lower their cost, and this bill would impose penalties on them and stop them from doing that."

According to Blumenthal, "the bill that Sen. Portman and I have advanced, since it's much more limited and discreet, could be attached to the defense authorization bill, which will be almost certainly voted on before the end of the year."

The latter refers to the legislation that annually authorizes funds for the Defense Department.

Said Blumenthal: " His - Leahy's - bill is broader, I don't know whether it will pass before the end of the year in this session, but I am very confident that it will be approved early in the next session."

Asked for comment, Leahy's spokesman, David Carle, said: "Senator Leahy is working hard to get the Trafficking Victims Protection Act reauthorized this year and has built strong bipartisan support for his bill … He welcomes the support from Sens. Portman and Blumenthal on this effort."

The Polaris Project, an organization seeking an end to human trafficking, estimates 27 million people, most of them young, are captives as a result of this practice. About 17,000 of them cross the border into the United States each year, according to the organization.