The Justice Department’s antitrust unit will lose its acting assistant attorney general when Sharis Pozen departs at the end of April.  The leading candidate to replace Ms. Pozen reportedly is William Baer, head of Arnold & Porter's antitrust group. Mr. Baer, a former director of the FTC's (Federal Trade Commission) competition bureau, would continue the government’s reinvigorated enforcement of the antitrust laws, recently seen in its vocal opposition to the proposed merger between AT&T and T-Mobile USA - a deal that collapsed last month. Politics Front & Center. A bitter fight looms between the White House and Congress over the nomination of a permanent antitrust chief.  The Senate must confirm the selection, and such votes typically slow to a crawl during a presidential election year.  As it is, the White House has expressed frustration with partisanship on Capitol Hill and the slow pace of Congress in confirming judicial nominations and executive branch positions. Without a Permanent Antitrust Head. The Justice Department has not had a permanent antitrust head since August 2011 when , when Christine Varney left for Cravath, Swaine & Moore and Ms. Pozen succeeded her as the interim antitrust chief. Ms. Pozen, who joined Justice in 2009 from Hogan & Hartson law firm, told the White House she didn't want the permanent post but would stay on until the ATT-T-Mobile deal was resolved. Impact on Government's Antitrust Campaign. The change comes at a time when the White House is strengthening antitrust enforcement - a reversal from the Bush Administration's weak record in this area.  Over the last several decades, the federal courts also have reduced the scope of the antitrust laws. The change also can translate in lost government funding.  In 2011, the Justice Dept collected more than $1 billion in fines and other monetary assessments.  The division recently secured a dozen guilty pleas in a long-running investigation into bid-rigging in the municipal bond market. However, legal experts say that an antitrust unit under Mr. Baer would remain aggressive.  As director of the FTC’s antitrust division from 1995 to 1999, Mr. Baer was seen as a strict enforcer of the antitrust laws, challenging mergers that included the combination of Staples and Office Depot. Other possible replacements for Ms. Pozen are:  (i) Richard Parker of O’Melveny & Myers;  and , (ii) and Seth Bloom, longtime aide to Senator Herb Kohl (D-WI) who heads the Senate antitrust subcommittee. For further details, go to:   [Dealbook, 1/23/12].