Bill Clinton is to address the US Democratic Party convention - his speech closely watched for signs of his commitment to Barack Obama's campaign.



The former president's wife, Hillary, lost to Mr Obama in her bid to become the Democrats' White House nominee.

She has now backed her rival and freed her supporters to rally behind him. A roll call vote of the states has begun, leading to his formal nomination.

Mr Clinton will be followed by Joe Biden, Mr Obama's running-mate.

Mr Obama has arrived in Denver, where the convention is taking place, but is not due to speak until Thursday.

The roll call of states taking place ahead of Wednesday's speeches will confirm his formal nomination as presidential candidate - the first African-American to be nominated for a major US political party.

He will stand against Republican John McCain in the 4 November presidential election.

The BBC's North America editor Justin Webb says the roll call will be an opportunity for Hillary Clinton's supporters to decide whether to fall in line, to unite as she asked them to on Tuesday, or to kick up a fuss and hold out for her.

Speaking to a crowd of about 3,000 people ahead of the roll call, Mrs Clinton released her delegates - supporters won by her during the primary election process - to vote for Mr Obama.

"This has been a joy. We didn't make it, but boy did we have a good time trying," she said.

Many in the crowd shouted back "No!" as she released them, but Mrs Clinton urged them to put the party first.

"We will leave Denver united," she said. "My goal is that we win in November."

The roll call for the nomination - in which each state, in alphabetical order, declares how many votes were cast for each candidate in the primaries - includes Mrs Clinton's name, in a bid to placate her disappointed supporters.

Experienced shoulders

In his address, Mr Clinton is expected to launch attacks on Mr McCain and on the Bush administration, particularly over the state of the US economy.

His speech will be closely scrutinised for signs of lingering resentment over the bruising primary Democratic campaign, which ended in defeat for his wife, correspondents say.

Wednesday's addresses are expected to focus on foreign policy and security.

Some observers say the topics have been weak points of Senator Obama's campaign so far.

Senator Biden, 65, is a veteran foreign policy expert who was chosen as vice-presidential candidate by 47-year-old Mr Obama partly on account of his experience.

Mr Obama will headline Thursday's convention speeches, having spent the first part of the week campaigning in battleground states, and will formally accept the party's nomination then.

'Unite'

Speaking at the convention on Tuesday, Mrs Clinton said the Democrats could not afford to lose to the Republicans.

"Whether you voted for me or voted for Barack, the time is now to unite as a single party with a single purpose," she said.

Some of the defeated candidate's supporters have suggested they will not vote for her former rival, but she asked them to remember why they were in the campaign.

Mrs Clinton accused John McCain of being indifferent to the economic slowdown and of failing to recognise the need for health and social reform.
BBC News