When the options are promising more funding for sick children or preserving the funding for booze and balloons at political conventions, the choice should be about as obvious as it ever gets in Congress.  

Which might be why the Senate didn’t even need to call the roll Tuesday morning. Instead, a quick voice vote was all it took to clear legislation (for President Barack Obama’s certain signature) that would end taxpayer subsidies for the presidential nominating conventions — and declare the $126 million saved during the next decade should be spent researching pediatric cancer and other childhood disorders.  

The bill was hailed by its Republican authors, and plenty of Democrats, as a compassionately conservative, common-sense application of Robin Hood’s principal. That would be taking from those who appear to be rich (the political parties, businesses and civic leaders who have used the federal money to cover much of the costs of recent gatherings) and giving to those who appear to be needy (the National Institutes of Health’s budget has flat-lined in recent years, complicating its ability to tackle new studies).  

But it’s a bit more complicated than that — at both ends of the trade-off. As a spur for medical research, the legislation amounts to only an unenforceable promise to add a drop to the bucket.  

The bill does not deliver any new money to NIH; instead, it only permits Congress to increase funding levels for pediatric projects through the appropriations process for the next decade. And the amount of new annual authority amounts to less than 0.05 of 1 percent of the agency’s $30 billion budget — which, by the way, has more than doubled in the past 15 years, a boon that very few other parts of the government have even dreamed about.  

As a poke at the political system, on the other hand, the measure will have some substantive as well as symbolic meaning.  

The change will obliterate one of the few remaining ways in which presidential elections are (to a very small degree) taxpayer funded. Most Republicans will hail that as a great thing. Most Democrats, and the advocates banded together under the “campaign finance reformers” label, will lament it would be better for the trend on public financing to be heading the other way. But all sides will agree that cutting federal spending, and the attendant government oversight, from the conventions will create yet another opening for the electoral process to be engineered to the liking of the people and businesses with the most to spend.  

Those who believe political money is like water flowing downhill — it will always find a route to filling the voids — will predict that corporations, politically engaged members of the 1 percent and luminaries from the not-yet-selected 2016 convention cities will readily donate what’s needed to replace the federal subsidy.  

That likelihood is one reason the parties have hardly lobbied to keep their subsidy. Sen. Tim Kaine of Virginia, a former chairman of the Democratic National Committee, was among the vocal advocates of the NIH bill. (It’s named after Gabriella Miller, a 10-year-old girl from his home state who advocated for research before dying last year .) And in 2012, the Senate voted 95-4 for a straightforward eliminate-the-convention-funds proposal. (One of this year’s most politically endangered incumbents, Democrat Mary L. Landrieu of Louisiana, was in the “no” quartet.)  

Each of the 2012 conventions was given $18 million, which could be used for anything from functionary payroll to floral arrangements. That amount was only barely matched by the private donations for staging the Democratic meeting in Charlotte, N.C. — from such local economic backbones as Wells Fargo, Bank of America and Time Warner. But organizers of the GOP gathering in Tampa, Fla., raked in three times as much as the federal payment — from corporations including Lockheed Martin, Microsoft, Chevron, AT&T and Google.  

(On top of all that, the government spends about $50 million on security at each convention, a line-item not touched by the new legislation.)  

The money for regular convention overhead that’s now being scrapped has come from the Presidential Election Campaign Fund, created after Watergate as an initial foray into public election funding. The money comes from the taxpayers who opt to dedicate $3 of what they owe annually — the Form 1040 checkoff that also provides matching funds to presidential candidates who agree to abide by campaign finance restrictions. (In 2012 neither Obama nor Mitt Romney took the money, which would have been $91 million each.)  

In the past four decades, of course, the amount of money raised and spent on campaigns has skyrocketed. And in one side effect, the conventions have changed from relatively straightforward party-building affairs, punctuated by the occasional big news story, into weeklong Bacchanalia punctuated by highly orchestrated speeches that generate minimal coverage.  

It is that evolution that has leaders in both parties at least considering a significant shrinkage of their convention footprints — for a start, by reducing the duration of official business to three days from four. In fact, three of the past four gatherings have been truncated that way: Hurricanes prompted cancellations of the Monday sessions for the GOP in 2008 and 2012, and Labor Day (combined with the funding shortfall) prompted the Democrats to put off their 2012 opening session for a day. (Obama used the day to get local volunteers to do campaign organizing.)  

If ending the taxpayer payments ends up as the default rationale for reducing convention durations, the legislation finalized Tuesday will have left a mark at least as visible as what a few government scientists might discover — if they’re ever given the extra money.  

Read Daniel Newhauser’s coverage of the legislation — and its political implications — here.