AS THE MASSACHUSETTS LEGISLATURE slogs to the finish line, having once again ceded its super Democratic majority, this time to a lame duck governor, it’s fair to ask how does this keep happening.

As someone who has observed the crazy rush at the end of session as both a reporter and a legislative staffer, I have a few ideas.

The first and most obvious is that deadlines tend to focus the mind at the task at hand, whether you are cramming for finals or negotiating a budget. That’s especially true in negotiations when one side is trying to win concessions.

Then there are the inter-branch rivalries. The phrase I often use with my journalism students is, “the executive branch proposes while the legislative branch disposes.” Back in the day when budget documents had printed shelf lives of hours I used to toss a spending plan into a trash can to demonstrate how lawmakers, who had been working on their own version for months, dealt with the document.

In a state with a strong two-party system, political considerations come into play. But the same holds true with one-party domination.

Democrats have held veto-proof majorities in both branches of the Massachusetts Legislature since 1993, after a brief surge in Republican senators following the election of Gov. William Weld in 1990. Yet every two-year legislative session of late seems to end in the same stalemate, even in years when Democrat Deval Patrick sat in the corner office.

That would seem to demonstrate there aren’t monolithic political views among Democrats – or the branches in which they serve. The House is considered more moderate than the Senate, reflected by moderate Speaker Ron Mariano of Quincy and liberal Senate President Karen Spilka of Ashland. But progressives in the House still make their opinions felt and garner occasional wins.

Nor should anyone ignore the institutional rivalries.

In 1999, it took 104 days to reach a budget agreement, a standoff over spending priorities that eventually required the intervention of Speaker Thomas Finneran and Senate President Thomas Birmingham, and a number of private November sessions on a cold State House balcony.

That dynamic is clearly playing out in this final week as a six-member conference committee is working to resolve seemingly irreconcilable differences over a perennial House bill legalizing sports betting. In the latest iteration, the Senate waited nine months to act on the House version. The measure is currently given a 60-40 chance of enactment.

Because conference committee deliberations take place out of public view, there’s no clear picture on the negotiations. But one thing is certain: Proposals are being passed around looking for concessions on either side. Horse trading is the key to process. So too is time, waiting to see who blinks first.

Here’s where it gets sticky.

Under the Constitution, a governor has 10 days to review legislation sent to their desk. Gov. Charlie Baker has various options, from line item vetoes on appropriation bills to offering amendments, to outright rejecting a bill. Lawmakers would need two-thirds majorities in each branch to override his actions.

But with the clock ticking down to midnight on Sunday, July 31 (more like 4 a.m. Monday, August 1, given end-of-session behavior), Baker holds all the cards. Anything that reaches his desk this week has to be acceptable to him to see the light of day.

Mariano has acknowledged the dilemma. But it goes beyond the traditional end of session crunch.

In the mid-1990s, lawmakers adopted rules designed to avoid lame duck sessions, where members who opted against or lost reelection can create mischief. In odd number years, sessions end by Thanksgiving. In the even years, when lawmakers are up for reelection, it is July 31.

But the problem really starts at the beginning of the two-year session. Despite a computerized bill filing system, it take months to make committee assignments, then send bills along for hearings. A summer recess in odd years also slows the pace.

Committee work is supposed to be completed by early February in even years, but, as with much of the legislative process, rules are often made to be suspended.

Last but by no means least, legislative schedules are made and enforced by a handful of leaders in each branch, often under the unofficial rule that nothing comes to the floor unless there are enough votes for passage.

How does this end? Ultimately, lawmakers should take a cue from Shakespeare.

“The fault, dear Brutus, is not in our stars / But in ourselves.”

Jerry Berger directs the Statehouse Reporting Program at Boston University.