Bernie Sanders supporters booed at mention of the name of Hillary Clinton as a Christian pastor opened the Democratic National Convention with a prayer for unity.
Later in the convention, some chanted the slogan from the Republican convention last week: "Lock her up."
The deep divisions among the US Democrats were visible for the world to see when Rev Cynthia Hale, senior pastor of the Ray of Hope Christian Church in Atlanta, Georgia, led the invocation at the convention in Philadelphia, Pennsylvania.
"Pray with me," she began.
Praising God as the creator of the world, she continued: "You are the God of the nations. Each one owes its existence to you. You made America the great nation that it is, filled with a diverse, gifted and enterprising people. We are a people who have ability to give leadership to the world and all other nations, at the same time operating as one nation under your name."
She lamented the nation's divisions, which had bred distrust.
"There is tension and dissension in the land. This is not your will for us and we know it.
"We have a responsibility to You to be a party that celebrates diversity, values all people and treats everyone with dignity and respect."
At this point there were cheers, but soon they turned to jeers.
"We have an opportunity O God to give undeniable evidence of our commitment to justice and equality by nominating Hillary Rodham Clinton as our candidate... "
Now there were boos from the Bernie Sanders supporters, although there was also cheering.
Hale interjected a defiant "Hallelujah!" and continued: "... as our candidate for the highest office in the land. God you have given us wisdom. Now give us courage for the facing of this hour."
More boos came from the Democrats and some Sanders supporters chanted: "Bernie Bernie Bernie." Others simply stood stony-faced and unresponsive.
Hale concluded with a heartfelt: "Unite us O Lord in one party. It is in your mighty name that we pray. Amen."
Sanders' supporters had been asked not to walk out at any point. The party is making an effort to attract the Christian and other faith votes.
Political journalist tweeted some of the reactions. One Sanders supporter held up a sign that originally said "Rise Together" but had been adapted to read: "We Must Rise To Get Her To Prison."
Others adapted "Stronger Together" signs to read "Stop Her".
Some even copied the "Lock Her Up" chant from last week's Republican convention:
During the first day, Sanders was also booed by his own supporters when he called on them to back Clinton.
The benedicton was delivered by a Rabbi, Julie Schoenfeld, executive vice-president of the Conservative Rabbinical Association. She did not mention Clinton, and there were no boos.
