Beneath the golden dome of the State House on Beacon Hill, the authority wielded by House Speaker Ron Mariano and Senate President Karen Spilka is close to absolute. Within their respective chambers, they invariably get what they want. No proposal comes up for consideration unless they want it to. No bill comes to a vote without their say-so. No budget is finalized until they assent. They and they alone decide who will chair each committee. And they see to it that nearly every important decision affecting the people’s business is decided unilaterally or behind closed doors, without public debate or dissent.

“Whereas Massachusetts had been a historical leader in transparency in government even prior to the nation’s founding,” observed Patrick Gleason in Forbes magazine last year, “today the Commonwealth is arguably the least transparent state government in the entire United States.”

That lack of accountability and transparency is essential to the House speaker and Senate president’s iron grip on the Legislature. So when Diana DiZoglio ran for state auditor last year on a promise to audit the House and Senate — to open their doors and books and let the disinfecting sunshine in — she was threatening the very foundation of the legislative leaders’ authoritarian power.

No surprise, then, that DiZoglio’s spirited efforts to audit the Legislature were met by an iron wall of opposition from both Mariano and Spilka. Yet far from being intimidated by the top lawmakers, DiZoglio is going over their heads: She is spearheading an initiative campaign to put a proposed law on the 2024 ballot giving the state auditor express authority to “audit the accounts, programs, activities, and functions directly related to … the General Court itself.” If the measure is approved by Massachusetts voters next year, Beacon Hill’s world will turn upside down. (The General Court is the formal name of the Legislature.)

That DiZoglio, who previously served in both branches of the Legislature, hasn’t hesitated to challenge the imperious Senate and House bosses, doesn’t surprise those familiar with her defiant history of not truckling to politicians with the power to injure her. What does come as a surprise is the striking coalition that has come together to support DiZoglio’s challenge to the Legislature.

For her initiative petition to qualify for the ballot, the auditor must amass some 75,000 signatures from registered voters. Then, assuming the Legislature refuses to enact the proposed law, she will have to gather another 12,000 signatures in the spring.

Signature drives are time-consuming and difficult. It can be a struggle to find supporters who are sufficiently motivated to stand for hours at busy street corners, at town dumps, and in farmers markets, repeatedly approaching passersby and asking them to sign a petition.

But DiZoglio has assembled a remarkable bipartisan alliance in support of her effort. Though she’s a staunch liberal Democrat, she reached out in September to Amy Carnevale, the new chair of the Massachusetts Republican Party, to ask for help. Carnevale told me she hesitated for only a moment before agreeing to back the auditor’s campaign. The GOP state headquarters in Woburn became a distribution center for signature sheets, and the party printed and distributed thousands of petition sheets to Republican activists. Scores of Republican town committee leaders participated in an online training session. Carnevale and former party chief Jennifer Nassour organized an event in Boston to turbocharge the signature drive.

No less remarkable, MAGA Republicans who are often at daggers drawn with the moderate state party leadership have set aside their differences to help ensure the success of the Democratic auditor’s ballot effort. Hefty donations have come in from Ernie Boch Jr. and Rick Green, both of whom were avid supporters of Donald Trump in the 2020 election. The Massachusetts Fiscal Alliance, a taxpayer watchdog, sent petitions to its 15,000 members.

At the same time, DiZoglio has given her fellow Democrats the courage to buck Mariano and Spilka. On Wednesday, the Democratic State Committee voted unanimously to approve a resolution backing the push to subject the Legislature to an audit. The party “endorses the state auditor’s initiatives, including any necessary legal action against any impediments to their audit efforts,” the resolution affirmed — a slap in the face to Mariano and Spilka. Support (and volunteers) have come as well from progressive grass-roots organizations, such as Our Revolution and Act on Mass.

The result: An army of 450 volunteers from across the political spectrum successfully gathered at least 84,000 certified signatures, considerably more than the total needed. At a time of bitter polarization and discord, DiZoglio has shown that it is possible to unite Republicans and Democrats, conservatives and liberals, Donald Trump fans and Bernie Sanders fans into a force for reform on Beacon Hill. That is a tribute to the auditor’s brashness no less than to her acumen. She wagered that Massachusetts voters are fed up with their secretive, unaccountable Legislature and its highhanded, condescending leaders. Looks like her bet is paying off.