Sen. Barack Obama received the endorsement Feb. 20 of the powerful Teamsters, the fourth major labor endorsement of his candidacy in a week. The other unions that endorsed him in the week leading up to the Teamster announcement were the 65,000 member International Brotherhood of Boilermakers, the 1.9 million member Service Employees International Union and the United Food and Commercial Workers.

The Teamsters endorsement followed a meeting between Obama and Teamster president James P. Hoffa in Austin, Texas where Obama, according to Hoffa, stated his intention to re-negotiate the North American Free Trade Agreement (NAFTA) if he is elected president. The labor movement views NAFTA as harmful to American workers and sees the deal as having caused an exodus of millions of good paying jobs out of the country.

The Teamsters represent 1.4 million members.

Labor’s support will be critical in the Democratic primaries in the coming period especially in Ohio on March 4 and Pennsylvania on April 22. Ohio and Pennsylvania have large numbers of union members with more than 15 percent of the workforce in Pennsylvania and more than 14 percent of the workforce in Ohio unionized.

Obama and Sen. Hillary Clinton, his rival, had both lobbied hard for the Teamster backing because of the union’s reputation as an effective fund raiser for candidates it endorses and because of its effective get out the vote programs.

Clinton also has a number of unions backing her campaign. Twelve unions that are part of the AFL-CIO back her as well as the United Farm Workers from the Change to Win labor federation.

But Obama also has the backing of AFL-CIO unions including – the Transport Workers Union and the Boilermakers. With the Teamster endorsement he has four of the Change to Win unions. SEIU, the UFCW and UNITE HERE are the other three. UNITE HERE was the first national union to endorse Obama.

In a telephone conference with reporters, Hoffa said that the deciding factors in the Teamster endorsement of Obama over Clinton were Obama’s electability and his promise to renegotiate NAFTA. The union’s board voted unanimously to endorse the Senator, he said. Hoffa noted that former President Bill Clinton had successfully pushed for NAFTA approval by Congress during his tenure in office despite fierce opposition from organized labor.

Hoffa elaborated on this aspect of his talk with Obama. He told reporters that he was satisfied that Obama will, if elected, call the President of Mexico and the Canadian prime minister and tell them he wants to re-negotiate the pact because it has caused loss of three million jobs in the U.S.

Hoffa said, “Obama is the first candidate since Ralph Nader (in 2000) to say it (NAFTA) is not fair to U.S. workers.”

He also said polling done by his union showed that Obama’s positions on NAFTA, health care and other issues “resonate with our members.”

Hoffa said the Teamsters concluded a round of polling of their membership just before the endorsement. It was the first poll of the membership that did not include former Sen. John Edwards who dropped out of the race, he said.

The Teamsters president said Obama was backed by a majority in the poll. He also said that a majority of Teamsters polled felt that Obama would do better than Clinton in a match up with John McCain, the presumed Republican presidential nominee.