Opinion polls show U.S. Senator John Kerry heading toward another victory this week in the race for the Democratic Party's presidential nomination.

The polls show Mr. Kerry leading by more than 30 percent in the state of Wisconsin, site of Tuesday's primary election.

Saturday, Mr. Kerry expanded his lead as the Democratic front-runner with easy caucus victories in the western state of Nevada and Washington, D.C., the nation's capital.

Mr. Kerry's chief rivals, North Carolina Senator John Edwards and former Vermont governor Howard Dean, were far behind in both contests.

All five remaining candidates are expected to attend a televised debate later Sunday in the city of Milwaukee.

Mr. Kerry has now won 14 of 16 contests for delegates to the Democratic Party national convention, where the party will nominate a candidate to challenge President Bush in the November election. With the nomination almost in his grasp, Mr. Kerry has kept his sights trained on the incumbent president. Saturday, he accused Mr. Bush of using negative campaigning to hide his poor record in the White House.

Some surveys show that Mr. Kerry would beat Mr. Bush if the presidential election was held today.

But aides say Mr. Bush plans to step up his re-election campaign earlier than planned, airing television ads that promote the president's accomplishments and drawing distinctions between him and Mr. Kerry.

Some of this information provided by AP.