President Barack Obama's keynote Asian trade push risks failing in a Senate vote on Thursday, a result that would threaten the administration's diplomatic pivot to Asia to counter China's rising economic and political clout in the region. Failure of "fast-track" legislation, which would grant Obama the power to speed the deal through Congress, would mark a huge blow for the president, who has made a deepening of ties with Asia one of his top foreign policy priorities. It would also be a large political setback for Obama, who has worked hard for congressional approval of the trade bill, even engaging in a highly public debate with Elizabeth Warren, a prominent Democratic senator who is popular with many progressives who form the core of his political base. A vote to advance debate requires 60 votes in the 100-member Senate. The bill itself would then face a lower, a majority-vote threshold for approval, and conversations with aides and senators suggest this week's vote will be tougher than last. Amendments to stop currency cheats and a raft of unrelated legislation are slowing the bill as Congress rushes to close deals ahead of the Memorial Day holiday. "Everything here makes it tougher; we just have to keep plodding ahead," said Senate Finance Committee Chairman Orrin Hatch. A week ago, Senate Majority Leader Mitch McConnell got 65 senators to agree to bring the measure for debate. However, at least three legislators who had previously supported the bill threatened to defect because of an impasse over the future of the federal government's Export-Import Bank, which provides support to U.S. exporters. Trading partners such as Japan have pinned their hopes of selling a Trans-Pacific Partnership that will cover 12 countries and 40 percent of the world economy on a "yes" vote that would lead to a speedy closing of the strategically important deal. All Tied Up With the Senate and House hurtling toward a 10-day Memorial Day recess at week's end, there were negotiations throughout the Capitol on fast-track and reauthorizing Ex-Im, which is due to close on June 30 if its mandate is not extended. Highway funding and domestic surveillance programs, which expire at the end of this month unless Congress acts, also found their way onto the crowded agenda, with Senator Rand Paul staging an hours-long speech against renewing the surveillance program, interrupting the Senate's work on fast-track. The result is that the debate over fast-track was bleeding into other issues. Some lawmakers are eager to insert measures into fast-track that would crack down on countries that manipulate the value of their currencies to make their exports more competitive, with a particular eye on TPP partner Japan. They want tough rules with real sanctions included in the bill, although Senate Finance Committee leaders have proposed an alternative that nods to legislators' concerns but that critics say lacks real teeth. The battle over trade caused the White House to threaten to veto fast-track if sanctions with bite were included in the bill. Of current senators, 51 signed a 2013 letter calling for enforceable currency rules in trade deals. Even if fast-track passes the Senate, it faces a tougher battle in the House. House Republican Matt Salmon, who is helping to round up support among conservatives, said a strong Senate majority would help his cause. "It's going to be a really heavy lift," he told reporters. (Reuters)