WASHINGTON: US presidential frontrunners Hillary Clinton and Donald Trump seek to deliver knockout blows against their rivals in Tuesday’s five high-stakes primaries, with pressure mounting to wrap up the nomination races and pivot toward the general election battle. Don’t expect the challengers to buckle just yet. The extraordinary 2016 race has tested American political tradition, with the Democratic and Republican parties taking their nomination battles deep into primary season. Clinton, aiming to become the nation’s first female commander in chief, faces a resilient liberal Senator Bernie Sanders, whose grassroots campaign to highlight income inequality has mobilized millions of young voters. But the ex-secretary of state is poised to extend her delegate lead Tuesday when Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island host their primaries. If Trump is able to snatch most of the Republican delegates at stake April 26, this would propel him much closer to reaching the 1,237 delegates needed to nail down the nomination against rivals Sen. Ted Cruz (R-Texas) and Ohio Gov. John Kasich.