Seattle Mayor Mike McGinn has been shedding pounds, but a new poll of Emerald City voters suggests that Hizzoner has also lost substantial public support this spring.

The poll by EMC Research shows that just 23 percent of those surveyed approve of the job McGinn is doing as mayor, while a whopping 73 percent term his performance as “fair” or “poor.”

Voters were split down the middle in feelings toward the mayor in an EMC survey taken in March: 46 percent viewed him favorably, 45 percent unfavorably. In the latest poll, taken last week, just 36 percent had a favorable view of McGinn: 56 percent now hold an unfavorable opinion.

McGinn is not yet halfway through his first term, but the poll indicates it’s likely to be his only term. Just 28 percent of voters surveyed said they would vote to reelect McGinn. Eleven percent were undecided, and a whopping 61 percent answered “Someone Else.”

A comparison of March and June poll figures is revealing.

In both surveys, just over 3 percent of those surveyed said McGinn was doing an “Excellent” job. In March, 30 percent termed his job performance as “Good” — a figure that has since plummeted to 19.5 percent.

The figures of those who say McGinn is doing a “Fair” job stayed fairly constant, 40 percent in March and 39.4 percent in June. But the number answering “Poor” has soared from 25 percent to 34.4 percent.

The poll of 500 likely Seattle voters, its results first reported Monday morning by Publicola, has a margin of error of plus/minus 4.4 percent.