Hillary Clinton
Democratic presidential candidate Hillary Clinton gives a thumbs up during a stop at the Lincoln Square pancake house as she campaign for votes on May 1, 2016 in Indianapolis, Indiana.Getty Images

Lone Republican candidate Donald Trump may have become the presumptive Republican nominee without much trouble, but polls show that a general election fight against likely Democratic candidate Hillary Clinton will not come as easily. A poll released early on 4 May shows Clinton leading Trump by 13 points nationally, while averages from current national and battleground state polls place her ahead by nearly 10 points.

In the latest CNN/ORC poll conducted ahead of Trump's key victory in Indiana, the former secretary of state leads the real estate mogul 54% to 41%. The poll also reveals that Clinton is considered better trusted in several issues, including terrorism, healthcare, immigration and climate change, The Hill reported. Trump leads in just one issue by 5%: the economy.

According to The Hill, 56% of voters view Trump unfavourably and 41% view him favourably. Meanwhile an equal 49% view Clinton unfavourably and favourably.

In another matchup conducted by The New York Times, Clinton maintains her lead and looks poised to take several key states in a general election. If Clinton becomes the Democratic nominee and holds her 10 percentage point lead, she could take each of the states won by President Obama in 2012 as well as North Caroline, the Times contends.

If Trump were to improve his polling margin by just five percentage points in each state, Clinton would still earn more electoral votes — 285 to 253. According to the NYTimes, Trump would need to improve his polling margin by 10 percentage points — bringing him to 305 electoral votes to Clinton's 233 — in other to win in the general election.

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The path to the GOP nomination cleared for Trump following the Indiana primary on 3 May when his chief rival Texas Senator Ted Cruz suspended his campaign. The remaining Republican candidate— Ohio Governor John Kasich — announced he was dropping his bid for the party's nomination the next day, leaving Trump as the only GOP candidate.

Meanwhile, Clinton continues to battle rival Vermont Senator Bernie Sanders, who vows to remain in the race until the Democratic National Convention in July. Clinton is less than 200 delegates away from clinching the nomination, while Sanders needs over 900 more delegates to reach the necessary 2,383 delegates.