A veteran US senator said Thursday that he expected the Senate to ratify this year the UN convention on the law of the sea, which supporters say will benefit US engagement in Asia.

Senator Joe Lieberman, an independent who is active on foreign policy, said that he felt a "pressing urgency" for the United States to ratify the treaty during recent visits to US-friendly nations in Southeast Asia.

"I am hopeful that by the end of 2012 the US Senate will at last vote on this treaty and ratify it," Lieberman told a conference at the Center for Strategic and International Studies.

"In my opinion, there are more than enough votes now in the Senate to ratify the convention," he said.

But Lieberman said that some senators "remain zealously opposed" and may use procedural maneuvers to block a vote. Ratification of a treaty requires a two-thirds majority in the 100-member Senate.

Lieberman said that the leadership of the Senate, where President Barack Obama's Democratic Party holds a slender majority, has decided to wait on a vote until after the November 6 election.

The United States is one of a dwindling number of countries that have not ratified the 30-year-old pact, which defines how nations can use the ocean and sets exclusive economic zones off coastlines.

The Obama administration has led a push for the Senate to ratify the treaty, arguing that it would help ensure US freedom of navigation as China rapidly expands its navy and tensions remain high in the Middle East.

The United States has frequently called on China to respect freedom of navigation in the conflict-ridden South China Sea, but critics in Asia note that Beijing, unlike Washington, has ratified the UN convention.

Some conservative Republicans oppose the treaty, saying that it would impinge on US sovereignty and restrict US businesses in certain cases, including access to undersea minerals.

But the US military top brass and business groups, including the US Chamber of Commerce, have urged ratification.