Elizabeth Warren narrowed Joe Biden's lead according to September's IBD/TIPP poll. The Massachusetts Senator is now within four points of the former Vice President, who remains the frontrunner.

Of note, IBD/TIPP was considered one of the more accurate polls during the 2016 US election - finding Trump ahead of Hillary Clinton during the last few weeks of their campaigns.

The same poll has Biden with a 12 point advantage over President Trump in 2020 in a head-to-head matchup, while Warren has a 3 point lead over the POTUS, according to Investor's Business Daily.

Elizabeth Warren had the support of 24% of registered Democrats and independents who lean Democratic, up from 17% in August. Joe Biden's support dipped to 28% from 30%. Meanwhile, Vermont Sen. Bernie Sanders came in a distant third at 12%, unchanged from August. Support for Calif. Sen. Kamala Harris sank to 6% from 11% in August. South Bend, Ind., Mayor Pete Buttigieg slipped a point to 5%. New Jersey Sen. Cory Booker had the backing of 4%, up from 2% in August. No other candidate polled more than 1%. Another 15% of respondents said they were undecided. -IBD

According to the poll, Biden - who can barely stay awake during interviews, has a 54% - 42% advantage over Trump. A month earlier Biden had a 13 point lead, while Sanders was ahead of Trump by 5 points, and Warren 3 points.

Among independents, Biden has a 55% - 37% advantage over Trump, while Warren comes in at 47% - 45% and Sanders at 51% - 42%.

In the Democratic nomination matchup, Biden polled 28% support among both women and men. Warren's support rose to 27% among women, but 19% among men. Warren led all candidates among whites, with 26% support to Biden's 24% and 14% for Sanders. That suggests early voting states of Iowa and New Hampshire, whose demographics tilt white, offer her a potential opening. Yet polling ahead of the Granite State primary has shown Warren trailing Biden and Sanders there. That could make Iowa's caucus a must win for her. -IBD

Among self-described liberals, 35% favor Warren vs. 18% for Biden, while Sanders came in at 14%. Biden is the clear winner among self-described conservative or moderate Democrats, as well as Black and Hispanic voters at 33%.

Younger voters aren't so sure about Biden, however. Sanders came in first among the 25-44 age group, while Biden came in third - however the former VP's popularity among older voters has placed him firmly in the lead for the Democratic nomination.

The IBD/TIPP poll surveyed 903 people from Aug 22 - 30, and has a margin of error of 3.3%.