Presumptive Democratic presidential nominee Joe Biden leads President Trump by 9 points nationally with the less than three months before the 2020 election, according to an NBC News-Wall Street Journal poll released on Sunday.

The survey, published just a day ahead of the start of the Democratic National Convention, showed that 50 percent of registered voters favor the former vice president, while just 41 percent say they'd vote for Trump. The findings represent little shift in public sentiment from a similar poll conducted in July that showed Biden with an 11-point advantage over Trump. 

The new survey was released just days after Biden selected Sen. Kamala Harris (D-Calif.) to be his running mate and as the U.S. continues to weather challenges posed by the coronavirus pandemic.

Biden carries double-digit advantages over Trump on handling issues such as the coronavirus and health care. Forty-nine percent of voters said Biden was better suited to handle the current health crisis, while just 33 percent said the same of Trump. Meanwhile, Biden leads Trump by 24 percentage points on handling race relations. 

Voters said Trump was better equipped to handle the economy and crime, however, according to the poll. 

“Clearly, Biden is in the lead. Clearly, Trump has a lot of problems,” Democratic pollster Peter Hart told NBC News. 

The new survey was conducted during and after Biden announced his vice president selection. The poll found that Harris holds a higher net approval rating (+4) than Trump (-12), Biden (-6) and Vice President Pence (-5). 

Thirty-nine percent of voters said they held a positive view of the California senator, while 35 percent said they had a negative view of her. Feelings about Harris divided starkly along party lines, with 71 percent of Biden voters saying they held a positive view of her and just 4 percent of Trump voters saying the same. 

In their first appearance together following the vice presidential announcement, Biden and Harris denounced Trump's response to the coronavirus and how he's handled race relations in the country. Harris also called out Trump's handling of the economy, saying, "Like everything else he inherited, he ran it straight into the ground."

National and state polls have continued to show Biden with substantial advantages over Trump in his bid for the White House. A "States of Play" survey from CNBC and Change Research released last week found Biden leading Trump in five of six battleground states, including Florida, Michigan and Pennsylvania. 

The NBC News-Wall Street Journal poll was conducted between Aug. 9 and Aug. 12 among a population of 900 registered voters. It has a margin of error of 3.3 percentage points.