A Republican National Convention delegate puts her fingers in her ears as other delegates scream and yell after the temporary chairman announced that the convention will not hold a roll-call vote on the Republican National Convention Rules Committee's report and rules changes and rejected the efforts of anti-Trump forces to hold such a vote, at the Republican National Convention in Cleveland, Ohio, US July 18, 2016. [Photo/Agencies]

CLEVELAND - The Republican National Convention briefly erupted in chaos on Monday when opponents of presumptive US presidential nominee Donald Trump stormed out of the room and others chanted in a failed attempt to force a vote opposing his candidacy.

The turmoil threatened efforts by the Trump campaign to show the party had united behind the businessman-turned-politician and distracted from the day's theme of "Make America Safe Again," meant to depict Trump as a strong leader capable of shielding the country from violence.

The convention's opening night featured a string of emotional speakers attacking Democratic presidential candidate Hillary Clinton's record as secretary of state under President Barack Obama, arguing she had made Americans vulnerable to Islamist militancy.

The anti-Trump forces interrupted the proceedings earlier in the day, seeking to change the party's nominating rules to allow delegates to support alternative Republican candidates over Trump.

Party leaders held a voice vote, then declared the opponents lacked enough support, triggering pandemonium on the floor of the Cleveland basketball arena where Trump is due to be formally nominated this week for the Nov 8 election.