Story highlights Hillary Clinton leads Donald Trump in a general election match-up, 49% to 39%, a new NBC/WSJ poll shows

Joe Biden would enter the race as the most popular of the major candidates

Washington (CNN) Hillary Clinton would beat Donald Trump in a general election match-up if the election were held today, a new poll shows.

Clinton beats Trump, 49% to 39%, head-to-head. She would be neck-and-neck with other GOP contenders -- including former tech CEO Carly Fiorina (45% to Clinton's 44%), retired neurosurgeon Ben Carson (46% to Clinton's 45%), former Florida Gov. Jeb Bush (44% to Clinton's 45%).

But if Vice President Joe Biden runs for president, he'd enter the race as the most popular presidential candidate, according to the NBC News/Wall Street Journal survey

Clinton's favorability rating is underwater: 39% of voters view her favorably, while 47% say they see the former secretary of state unfavorably.

But Trump's problem is much bigger. He's seen favorably by 25% of the general electorate, compared to unfavorably by 58%.

Read More