Denver, Colorado - Demanding equal pay for equal work and affordable health care for all, Senate women took the podium Tuesday at the Democratic convention to offer their support for Barack Obama's presidential campaign.

New York Senator Hillary Clinton, who narrowly lost the centre- left party's nomination to Obama, introduced the senators in a video appearance and is to make her own appeal for party unity later in the evening.

The night was devoted to the economy and women's issues. Tuesday was the 88th anniversary of the US women's right-to-vote amendment to the US constitution, and the Democratic speakers emphasized the importance of women's support for Obama in the general election battle against Republican candidate John McCain.

Senator Barbara Mikulski of Maryland, a feisty advocate for women's rights, noted that women still earn only 77 cents for every dollar men earn.

"Let's elect Barack Obama and finally get equal pay for equal work," she said. "We can put change in women's checkbooks."

The reference to "change" echoed Obama's campaign motto: "Change we can believe in."

Senator Barbara Boxer of California said that Democrats must wrest a large-enough congressional majority in the November general elections to break down "Republican roadblocks" to measures to fight global warming.

Another item on the women's Checklist for Change was affordable healthcare and coverage for the nation's more than 40 million uninsured.

"We are in the midst of a national healthcare crisis," Senator Blanche Lincoln of Arkansas said. "Two-thirds of Americans have trouble getting or paying for the care that they need."

Clinton's historic bid for the Democratic nomination brought her more than 40 per cent of the 4,400 delegates assembled in the Rocky Mountain city of Denver, Colorado.

Tension over her role at the convention and in the general election campaign continued during the four-day event, which ends Thursday with Obama's acceptance speech as the country's first African-American major party presidential nominee.

Monday was devoted to sculpting a personal profile of Obama, as his wife, Michelle, spoke of their working-class roots and the legacies of the movements for women's and civil rights, which brought the couple to the threshold of the White House.

Former president Bill Clinton, Hillary's husband, will speak Wednesday night. It was not clear if the traditional state-by-state roll call would run its full course and allow Clinton's delegates to give her a final, full-throated tribute.

Clinton has urged her delegates to support Obama. (dpa)