Deval Patrick has become the clear front runner for the Democratic nomination for governor, and Kerry Healey would lose to any of the three Democrats if the election were held today, according to the latest State House News Poll.The scientific phone survey of 410 Massachusetts adults was conducted June 28-30 and carries the following margins of error: plus or minus 4.7 percent for the whole group, plus or minus 5.1 for the subgroup who said they are registered voters; and 7 percent among those saying they are likely to vote in the Democratic primary.Among that latter group, the outstanding feature is how far Thomas Reilly has fallen. Since March, when Patrick polled 21 percent, Attorney General Thomas Reilly has dropped from 43 percent to 19 percent, with his support absorbed both by Patrick and latecomer Christopher Gabrieli.Those who said they were likely to vote in the Democratic primary preferred Patrick by 35 percent to Gabrieli's 22 percent and Reilly's 19 percent. This was the first major statewide poll to show Reilly in third place.This poll confirms the findings of a recent Channel 7/Suffolk University poll showing Reilly dropping fast and Patrick the front runner. One poll alone is not a good barometer, but when multiple surveys show similar results, sheer mathematics indicates the trend being detected is a real one. All three Democrats defeated Lt. Gov. Kerry Healey by small but noticeable margins in hypothetical matchups, with Patrick running the strongest: 40 percent to 31 percent for Healey; Reilly ran the weakest, with 36 percent to 31 percent for Healey.