Hillary Clinton has begun drawing up a battle plan for defeating Donald Trump in the US presidential election, which will draft her husband and President Barack Obama into the front line of her offensive.As she tries to become the first female US president, Clinton will portray Trump as a misogynist with a temper and who ruthlessly preyed on the working class to make his billions.Trump and Clinton took big steps towards securing their parties' presidential nominations on Tuesday with a series of state-by-state victories, but their rivals vowed to keep on fighting.On Super Tuesday, the 2016 campaign's biggest day of state-by-state nominating contests, Trump, 69, and Clinton, 68, proved themselves the front-runners to succeed Democratic President Barack Obama.Now they are under pressure to show that they can unify voters in their respective parties before the November 8 election and, in Trump's case, avoid a split in Republican ranks.Trump won seven states, with victories from the Deep South to Massachusetts adding to his momentum of last month when he won three of the first four contests.Clinton's victories, also in seven states, and in the South Pacific territory of American Samoa, were just as impressive but in many ways predictable. She was propelled by African-American voters in southern states such as Arkansas, where she and her husband, former president Bill Clinton, began their political careers.Trump's rivals, US senators Ted Cruz, of Texas, and Marco Rubio, of Florida, said they were determined to stay in the race.Cruz, 45, won Texas, Oklahoma, and Alaska, bolstering his claim that he had the best chance of stopping the New York billionaire.Rubio, the Republican establishment's favourite, was the winner in Minnesota, his first victory in the nominating contests.Clinton rival Bernie Sanders, a US senator from Vermont, won in his home state and in Colorado, Minnesota and Oklahoma, but lost to her in Massachusetts, which he had hoped to win.The "democratic socialist" vowed to pursue the battle for the nomination in the 35 states yet to vote...