It was not the result Hawaiian Electric Industries Inc. hoped for Tuesday.

The state’s largest electric utility failed to get the necessary votes at its shareholders’ meeting to approve its planned $4.3 billion sale to Florida-based NextEra Energy Inc.

So HEI extended the voting deadline to June 10 and commenced a monthlong campaign to get another 5.4 million shares to line up in favor of the proposed sale.

"It’s roughly a month delay," said Connie Lau, HEI’s president and chief executive officer, following the meeting.

HEI appealed to shareholders in a news release Tuesday: "HEI shareholders — your vote is important — please vote for the merger with NextEra Energy today."

NextEra offered to buy HEI in December. The deal must first be approved by HEI shareholders and the Hawaii Public Utilities Commission.

HEI has argued the much larger NextEra could bring added resources to the state, lower electrical rates and speed up Hawaii’s move away from fossil fuels for electric power. Hawaii has the highest electrical rates in the nation in part because 86 percent of the Hawaiian Electric Cos.’ electric power comes from burning oil and coal.

The sale of HEI to Next­Era has raised concerns about control of a key player in the state’s economy moving to the mainland and the cost of the deal being placed on the shoulders of HECO customers.

Leonard Tam, an HEI shareholder for over 30 years, said he voted against the sale because he doesn’t want control to shift to Florida.

"What they do here is totally different than what they do in Florida," Tam said. "I appreciated the reliability of the Hawaiian Electric Co. for 100 years. We had good electricity and reliable electricity."

If HEI doesn’t get the votes required to move forward with the sale by June 10, it can extend the deadline again.

What has made it difficult is, under Hawaii law, HEI needs the owners of 75 percent of all outstanding shares to vote for the sale. In many cases a sale can be approved with only a majority of the outstanding shares voting in favor.

As of Tuesday 70 percent of HEI shares had been voted in favor of the sale, about 8 percent were voted against and 22 percent, or 23.7 million shares, had not been voted.

Lau said 90 percent of the shares that have been voted have gone in favor of the sale. So if the company can get more shareholders to vote, it should be able to pass the 75 percent threshold.

Lau said some shareholders may have skipped the vote because it’s a busy time of year.

"Now it’s the busiest proxy season time and graduation," she said. "So we thought we would give ourselves another month to solicit more votes. Even me, during this proxy season my mailbox is getting stuffed with annual reports and proxies."

Andrew Dahlburg, an HEI shareholder who voted in favor of the sale, said he was disappointed the sale wasn’t approved Tuesday.

"Usually people just throw (the proxy or ballot) away. They have all of these outstanding shares. It’s disappointing. That’s why they canceled the meeting," Dahlburg said. "I think Hawaii needs the technical assistance" that NextEra could provide. "This is a big moment for the company."

Jeff Watanabe, chairman of the board of HEI, said he is confident the company will receive the needed approval if all outstanding shares vote.

"We’re trying to make sure that those people who have the shares have the chance to vote. We want to make sure that they understand that their vote is important," Wata­nabe said. "We think that if we get them to vote, if they follow the same pattern of 90-plus percent of people who do vote, voting in (favor of) the transaction, that will carry the day."

NextEra said it is confident the sale provides value to shareholders.

"We remain confident that the combination of NextEra Energy and Hawaiian Electric delivers compelling value for HEI shareholders, customers and local communities, and will strengthen and accelerate Hawaii’s clean energy transformation," said Rob Gould, spokes­man for Next­Era.

Despite falling short of the required approval, Lau said more shareholders participated in the vote than in the past.

"More of our shareholders, who would not normally respond for an annual meeting, actually did vote. But we have this unusually high vote requirement under Hawaii law where we have to get 75 percent of outstanding," Lau said. "We have to get 75 percent of everybody out there, even those people who don’t normally vote."

Timothy Winter, financial analyst with Gabelli & Co., said the required 75 percent supermajority approval is unusual.

"I haven’t seen many shareholder votes with that high of a threshold," he said. "That’s a high number, but I would say we weren’t surprised by the results. We are encouraged because 90 percent were in favor."

Winter said HEI’s challenge will be to reach the average shareholder who may not be aware of the vote.

"When you look at the numbers, clearly shareholders are in favor of the merger. It is hard. It is a challenge … to get people to put forth the effort to vote and mail it in, your average shareholder with 200 or 300 shares. People’s lives are busy; they have more important things. It’s not even brought to their attention. Some may not even know about it."

Winter said he believes that the month could provide enough time to reach all shareholders.

"One would think that it can be accomplished," Winter said. "You would certainly be in the realm of a reasonable and manageable thing to do."

The next meeting will be held at 10 a.m. June 10 in Room 805 on the eighth floor of American Savings Bank Tower at 1001 Bishop St. in Hono­lulu.

CORRECTION: NextEra has been running advertisements touting the advantages of this deal. An earlier version of this story said HEI had been running the ads.