By Andrea Hopkins

DENVER (Reuters) - Union leaders know that ringing speeches at this week's Democratic Party convention will not in themselves win over white working-class Americans reluctant to elect Barack Obama the first black president of the United States.

That's going to take one-on-one persuasion and a closer focus on pocketbook issues that the party hopes will trump racial concerns and win backing from critical blue-collar swing voters before the November 4 election, they said.

Obama's troubles with white working class voters have been overshadowed at the convention by the party's struggle to bring into the fold disgruntled supporters of his defeated rival Democratic Hillary Clinton.

But union leaders talk more about the need to overcome racial prejudice to rally working class voters behind the 47-year-old Illinois senator in the close race with Republican John McCain, 71.

"Many folks around the country have never voted for an African-American, not for president," Karen Ackerman, the political director of the AFL-CIO trade union umbrella group, told reporters on the convention sidelines.

"But we are confident Barack Obama will be elected when working class voters know who he is and what he stands for." The AFL-CIO, like most other labour groups which traditionally back Democrats, has endorsed Obama.

A survey released this week showed that while black and Latino workers support Obama by wide margins, white working Americans are almost evenly split, with 43 percent supporting Obama and 44 percent McCain.

But the poll, by Lake Research for the Change To Win union group, also indicated a way to bridge the racial divide: 40 percent of working Americans said the economy was their top concern this election year.