A new poll has confirmed that Sen. Bernie Sanders (I-VT) has caught Hillary Clinton in the California primary, reaching a statistical dead heat with less than a week to go before the June 7 primary.

The NBC News/Wall Street Journal/Marist poll, released Wednesday, shows Clinton with 49% support from likely Democratic voters and Sanders with 47% — well within the poll’s margin of error of 4.2%.

The poll was conducted May 29-31 among 557 likely Democratic primary voters. Significantly, Clinton is ahead, 58% to 41%, among those who have voted already. The state began sending mail-in ballots to most voters in early May; roughly two-thirds of voters are expected to cast their ballots early. That means Sanders’s late surge may not be enough to outweigh Clinton’s support among early voters.

NBC elaborates:

In the Democratic horserace, Clinton leads Sanders among likely voters ages 45 and older (63 percent to 33 percent), self-identified Democrats (57 percent to 40 percent), women (54 percent to 41 percent), past Democratic primary voters (53 percent to 42 percent) and whites (51 percent to 46 percent). Clinton also is ahead among those who have already voted, 58 percent to 41 percent. Meanwhile, Sanders leads among first-time participants (72 percent to 28 percent), independents (68 percent to 26 percent), those younger than 45 (66 percent to 30 percent), men (54 percent to 43 percent) and Latinos (49 percent to 46 percent).

Clinton’s lead among self-identified Democrats may prove decisive. Sanders attracts more independent support, but independent voters will need to make a special request in order to receive a ballot on which they can vote for the Democratic presidential candidate — and many Sanders supporters may not know how to do so.

Sanders will take heart from the fact that he leads among Latino voters in a poll for the first time — a significant breach in Clinton’s firewall among minority voters.

NBC notes that Sanders is ahead, 48% to 47%, if “all potential Democratic voters” are included — but that is not a rigorous polling measure, and is difficult to extrapolate to actual ballots.

An effort by Sanders supporters to have the state’s voter registration deadline extended was rejected by the courts on Wednesday. The registration deadline was May 23 — except for new citizens, who may register until June 7.

Last week, the Public Policy Institute of California also found Sanders trailing Hillary Clinton 46% to 44%, also within the margin of error.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new e-book, Leadership Secrets of the Kings and Prophets: What the Bible’s Struggles Teach Us About Today, is on sale through Amazon Kindle Direct. Follow him on Twitter at @joelpollak.