Washington state regulators have denied a request from Hydro One and Avista Corp. to reconsider the rejection of the Ontario utility's planned multibillion-dollar takeover of the American company.

The Washington Utilities and Transportation Commission says it will take no action on the request, which was made after regulators found the $6.7-billion planned merger would not adequately protect Avista customers from political and financial risk.

The commission had said it would not approve the deal for fear the Ontario provincial government, which owns 47 per cent of Hydro One's shares, might meddle in Avista's operations.

It cited Premier Doug Ford's move to force former Hydro One CEO Mayo Schmidt to retire, which was followed by the resignation of the entire board, as evidence that the province was willing to put political interests above those of shareholders.

In December, Hydro One and Avista said in their request for reconsideration that the commission erred in reaching its decision because it "misapprehended" the political risks Ontario's ownership stake in Hydro One posed.

Last week, the Idaho Public Utilities Commission also denied the proposed takeover, finding that the companies had failed to demonstrate that the transaction met the public interest and no-harm tests set out in the state law.