The Democratic presidential nominating process is now at its halfway point, but fear over the spread of coronavirus has slowed the race for the White House to a virtual standstill. Right now, 25 states along with the District of Columbia, Puerto Rico, Guam and the Virgin Islands have yet to hold their nominating contests, but state and party officials are grappling with how best to address the primary process amid health concerns.

To clinch the Democratic nomination, a candidate needs to obtain 1,991 pledged delegates, just over half of the 3,979 at stake. On Tuesday, Illinois, Florida and Arizona doled out 441 pledged delegates. By CBS News estimates, on Wednesday, Joe Biden was leading Bernie Sanders in total allocated delegates, 1,093 to 802. That means 1,668 delegates, just under half of the pledged delegates available, are still up for grabs.

States changing contests

Five states have so far postponed Democratic presidential primaries. Ohio was slated to hold its primary on March 17, with 136 pledged delegates available. It has moved in-person voting to June 2.

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Georgia was scheduled to hold its primary on March 24 and has 105 pledged delegates at stake. The state has now moved its contest to May 19. Louisiana's April 4 primary, with 54 pledged delegates available, will now take place June 20. Kentucky pushed back its May 19 primary, with 54 pledged delegates to be allocated, to June 23. And Maryland Governor Larry Hogan announced Tuesday the state's primary will now be held on June 2, pushed back from April 28. Candidates will be vying for 96 pledged delegates.

Wyoming has canceled its in-person caucuses but is still allowing voting by mail. And voters may still pick up ballots and drop them off at designated locations between March 28 and April 4.

Puerto Rico's Democratic party has requested to move the primary from March 26 to April 26. On Monday, the Puerto Rican Senate approved the request, and the House of Representatives will vote on it Thursday, and the Governor will have the bill late Thursday evening or Friday. The chairman of the party Charles Rodriquez anticipates it will pass, and the governor will sign it.

States moving forward with April primaries — for now

The next primaries are to take place in nearly three weeks, on April 4. Hawaii and Alaska are, as of now, going forward with their primaries on the fourth, and Wisconsin will hold its primary on April 7. The three states have 15, 24 and 84 pledged delegates to be allocated, respectively.

Five primaries are currently slated for April 28, including Connecticut, Delaware, New York, Pennsylvania and Rhode Island. New York has the largest delegate haul with 274, followed by Pennsylvania with 186. While officials have said the situations are being monitored, all five states are moving forward with scheduled contests.

Delegates

After Tuesday's primaries, almost 60% of the delegates to the national convention have been allocated. The next largest delegate prize is New York, which has 274 delegates up for grabs in its primary on April 28.

The Democratic National Committee said in a statement that it is working with state parties to adjust their delegate selection plans in response to coronavirus, but moving the contest could result in the loss of up to half of its delegation to the national convention.

The rules state that all presidential preference contests should take place by June 9, and all delegates must be elected by June 20. As of now, Louisiana and Kentucky risk losing some delegates. Ohio and Maryland have settled on June 2, in part because of the rules for the Democratic National Convention in Milwaukee, according to the statements by their governors.

In some states, electing the actual people to fill the delegate slots awarded to each candidate takes place after the presidential preference primary or caucus, so state parties need time before June 20 to hold state conventions to elect delegates to send to Milwaukee in July.

Already, some of these conventions have been postponed because of the coronavirus. For instance, the next step for Iowa's delegate selection process was its county conventions, slated for March 21, but the state Democratic party said the events will now be postponed to a future date to be determined.