Republican lawmakers say the results of a state Senate investigation into Sound Transit found that the agency misled lawmakers and the public while trying to pass a $54 billion transit package. But Democratic Senators who serve on the Law and Justice Committee that conducted the investigation say they don't agree with the findings released on Monday.

“Sound Transit played fast and loose with the truth,” Sen. Mike Padden, Republican chair of the Senate Law and Justice Committee, said in a release. “It kept key facts from the Legislature and the voters. It displayed disregard for laws designed to ensure full disclosure and prevent public resources from being used for campaigns.”

The probe, led by Republican lawmakers, investigated whether Sound Transit deliberately hid the cost of the tax package known as Sound Transit 3, or ST3.

Related: Lawmakers hold second investigatory hearing into Sound Transit, ST3

The ST3 measure approved by voters last November will pay to expand mass transit in King, Pierce, and Snohomish Counties.

The state Senate Law and Justice Committee found that the agency concealed the true cost of the ST3 measure, by going to the public with a larger tax package than originally pitched to the legislature. In 2015, Sound Transit proposed a tax package that would generate $15 billion over 15 years. However, the ST3 measure called for a much larger package that covered 25 years of new revenue.

The investigation also found Sound Transit improperly used public resources to promote a third-party campaign for a ballot measure.

The committee asked lawmakers to consider legislation to give taxpayers substantial tax relief and restrict agency campaign activities, such as advertising budget and lobbying. It also advised potential campaign violations be referred to a prosecutor’s office.

Sound Transit called the investigation a “highly partisan endeavor” that “perpetuates fictions” about ST3.

“The committee’s final report is a sham that the minority members did not even have a chance to review before its release,” Sound Transit spokesperson Geoff Patrick said in a statement.

Sound Transit has also said it was completely transparent about all aspects of the ST3 ballot measure, and points to the following documents as evidence of that:

Chronology of ST3 development

Memo to Sound Transit Board on Senate work sessions

Sens. Jamie Pedersen and David Frockt, both Seattle Democrats who serve on the committee, said they did not know the Republican-led committee would be releasing the investigation findings on Monday.

"Absolutely not. And these aren't even the findings of the committee, because for it to be a committee report, we'd have to have had hearings where we had a draft report to consider and an opportunity for minority members to make comments or draft a minority report, and we haven't had any of that process," said Pedersen. "This is purely a political effort by the Senate Republicans."

In response, Senator Steve O'Ban, R-University Place, who serves as the committee's co-chair, said that Democratic committee members were involved "at every step of the way" and are free to write up a minority report. O'Ban maintains that the findings released Monday are supported by a majority of the members of the Law and Justice Committee.

Pedersen said that after sitting through hours of testimony during the Law and Justice Committee's investigation, he does not believe that Sound Transit misled lawmakers or the public.

"Frankly, I think there was not a lot of evidence to support the allegations," he said. "I think this investigation was a waste of taxpayer money.

He and Senator Frockt also questioned the timing of Monday's announcement. It comes just two weeks before voters on the Eastside are set to choose a new state Senator to serve the 45th Legislative District. It's a race that will ultimately determine the balance of power in Olympia.

It's also a race in which Sound Transit and the car-tab controversy have been major issues. Pedersen believes that's part of the reason Republicans wanted to release the findings of their Sound Transit investigation right now.

"I think it's hard to conclude otherwise than this is meant to influence people's views on the ballots that dropped last week," said Pedersen. "I was surprised and frankly it seemed like a new low even for Senate Republicans."

Senator O'Ban disputed that claim as well.

"We could have waited for everyone's signatures," said O'Ban, referring to Law and Justice Committee member signatures. "But that would have delayed the release of the findings until just before the election. We wanted to keep politics out of it, because the issue of government misconduct is too important."

O'Ban has said he plans to re-introduce legislation that would require the direct election of Sound Transit board members when lawmakers return to Olympia next year.