Donald Trump's tough talk on law and order in a time of growing national insecurity in the US appears to be winning over some of his fiercest sceptics. As Trump hones his message, the challenge is to make it resonate among undecided female voters, who are crucial to his hopes of winning the US presidential election in November.Turmoil on the streets, both abroad and at home, could give Trump a new opportunity to do just that.He tried to seize it on Monday at the Republican national convention with several women speakers, including his wife, Melania, focusing on security.She told the convention that her husband would offer the country new leadership and keep it "safe and secure". Americans have been rattled by recent attacks in France and Florida, and the murder of police officers in Texas and Louisiana, polls show."We're not electing a husband, we're not electing a preacher, we're electing a leader," said Kay White, a Republican delegate."Security," she said. "Nothing else matters."A year ago Penny Nance, president of Concerned Women for America, a conservative advocacy group, was a blistering critic of the thrice-married Trump because of comments he made about Fox News anchor Megyn Kelly that many felt were sexist.But Nance now supports Trump and says the candidate can fashion an effective message for women centred on national security."Every day we wake up and get our kids ready for school and the television is on and there is another attack," she said.For Trump, independents will be a tougher sell. A majority of women who identify as "independent" continue to hold an unfavourable opinion of him.According to a recent Reuters/Ipsos opinion poll, 15.64% of independent women voters expressed a "very unfavourable" or "somewhat unfavourable" view of Trump. That compares with 89% of Democratic women voters and 31% of Republican women voters who have a similarly unfavourable view of the New York mogul.Trump has had trouble convincing women nationally to support him ever since he entered the race last year. Among women expected to vote on November 8, a majority expressed an unfavourable opinion of him every time they were asked in polls.Jen Lawless, director of the Women and Politics Institute at the American University, said she doubted Trump could rehabilitate his image with most women voters, saying his conflict with Kelly, in particular, had done lasting damage."I think that ship has sailed," she said. ..