As deadline to-do lists go, this one is light.

The Texas House’s calendar — its agenda or list of bills that it will tackle on a given day — is usually pages and pages long at this point in a legislative session.

It’s often full of portentous stuff. Tuesday’s is no exception, with a major piece of ethics reform legislation, a proposal to allow concealed handguns on college campuses in Texas and an abortion bill with enough political weight to nearly bring a handful of officeholders to blows the other night.

Tuesday is an important deadline — major legislation that started in the Senate has to get a favorable vote in the House by midnight to stay alive. Smaller stuff — bills with only local impact or that have no discernible opposition — gets one more day.

Lawmakers go through the calendar in order. And just like the line at the box office or your favorite barbecue joint, the fate of those at the bottom of the list depends on how things go at the top of the list. Whatever is still waiting for attention at midnight is out of luck.

What the Legislature has to do this session and what it wants to do are neatly divided this year. The must-dos aren’t imperiled by Tuesday’s deadline. All of the legislation is important to somebody — it got filed, after all, and made it this far. But several bills are politically important to many lawmakers and could easily figure into next year’s primary and general elections. A couple of those top items are doozies that could prompt clock-devouring debates.

• Senate Bill 19 is, or might be, a major ethics reform bill. Near the beginning of the session, Gov. Greg Abbott called on lawmakers to make ethics reform the centerpiece of the 84th Legislature. He has remained relatively quiet on the subject since then, but the House is ready to consider a bill that includes some of his ideas, some of the Senate’s and a load of proposals that came from the House. The list, in no particular order, includes more extensive disclosure of officeholders’ income and their business arrangements with companies doing government business; revolving door restrictions that would keep lawmakers from immediately joining the lobby; disclosure of donors to political nonprofits; expanded disclosure when lobbyists feed or entertain officeholders; and even drug testing for political candidates.

• Senate Bill 9 is an attempt to tighten the constitutional limit on growth of spending from one two-year budget to another. And as is the case with the current limit, the argument is over what ought to be included in the formulas. Lawmakers want to tie the hands of future budget writers without tying them so tightly that the state can’t function, and might also require a supermajority of the Legislature to sign off before the limits can be ignored.

• Senate Bill 11 would allow those with concealed handgun licenses to carry their guns on public college and university campuses in Texas.

• Senate Bill 575 would prohibit health insurance plans sold on the federal Affordable Care Act’s marketplace from covering non-emergency abortions. Only after those debates are over — quickly or slowly — will the House turn to the dozens of bills that fill out the rest of its last big calendar of the year.

Monday, June 1, is the final day of the session, and the days in between now and then are loaded with smaller deadlines. But Tuesday’s is a big one. Major bills that haven’t passed both the Senate and the House die when the clock strikes 12. A few might be revived as amendments. Most of them won’t.