Tom DeLay, the Republican leader known as "The Hammer" for his brass knuckles style, stood before a jury Monday and declared he never crossed the line into criminally dirty politics.

"Ladies and gentlemen, I am not guilty," the former US House majority leader said after an indictment was read accusing DeLay of money laundering and conspiracy.

The trial began a day before US voters head to the polls for mid-term elections in which Republicans are expected to retake the House of Representatives and cut deeply into the Democrats' Senate majority.

At the heart of the case is one transaction: DeLay's political committee in Texas sent 190,000 dollars of corporate donations to the Republican National Committee, which in turn donated the same amount to seven Texas candidates supported by DeLay.

Texas law prohibits corporate giving to candidates.

In opening statements, prosecutors and defense attorneys argued about whether the corporate money DeLay raised was part of a scheme to tilt the 2002 elections in Texas or a routine legal transaction.

The pivotal contest became the first step in DeLay's plan to redraw the state's congressional districts and tighten his grip on the leadership post by enlarging the Republican majority in Congress.

By 2004 DeLay had accomplished all of that, but a year later a Texas grand jury handed up the felony indictments arising from one transaction during the election.

DeLay was forced to resign his leadership post because of the indictment. He retired from Congress, after 22 years, in the middle of his reelection bid in 2006.

Texas prosecutor Beverly Mathews called the money "dirty" and part of DeLay's "larger, clever scheme" to change the face of the state's representation in Congress.

Dick DeGuerin, DeLay's lawyer, rebutted: "This case is about politics."

If convicted, DeLay he would face punishment ranging from two years probation to 99 years in prison, plus fines.

Mathews told jurors that DeLay's alleged illegal campaign activities had a larger purpose: An unusual mid-decade redistricting plan that would elect more Republicans to Congress and, by extension, bolster DeLay's leadership role.

"We are going to prove to you that Tom DeLay broke the law," she told the jury.

DeLay's attorney insisted the transactions were legal, and typical.

"You cannot convict Tom DeLay because of his politics," DeGuerin said.

"And no evidence will show any act done by Tom DeLay other than politics -- good politics, successful politics."

The trial is expected to last at least three weeks.

Both sides have subpoenaed a long list of Texas political leaders, Washington lobbyists, and representatives from the corporations that financed DeLay's political committee.