Darkness after work. Freeze warnings at night. Congress looking likely to work until close to Christmas, then return just a week into January. Staff and member travel clipped by the sequester. And an off-year election jump-starting the next presidential race earlier than ever.

No wonder that not-so-idle Capitol Hill speculation has already started about which two buffed-up and generous cities might get to welcome the Washington diaspora in the summer of 2016. That’s when thousands of lawmakers, aides, lobbyists, money chasers, journalists and functionaries are counting on at least one expense-account-funded week of networking and partying.

The presidential conventions are the holy grail of trade shows for the political-industrial complex, which is why talk about the 2016 locale options got started as soon as the crowds scattered last September from sodden and spread-out Tampa, Fla., and sweltering and just-as-spread-out Charlotte, N.C.

The volume under the chatter turned way up 10 days ago, when Las Vegas announced the formation of a full-fledged campaign to secure the Republican National Convention. It’s a high-risk, high-reward proposition for the GOP. There’s the obvious cognitive dissonance problem with anointing the nominee of an increasingly conservative party in a place called Sin City. But there are also 150,000 close-in hotel rooms, a promised new arena on the Las Vegas Strip and the possibility of helping win back a Hispanic-rich swing state.

None of that matters to many of the bit players inside the Beltway, whose only interest is in outdoing themselves in living up to the unofficial motto of the quadrennial gatherings: What happens at the convention stays at the convention. And the all-too-obvious ways for Vegas to make sure those bacchanalian wishes come true, 24 hours a day, will probably drive the GOP high command soon enough into the arms of on its more staid suitors.

Even if the nightlife isn’t quite as up to date in Kansas City, Mo., — the other early front-runner among the cities vying only for the RNC — convening there might at least lock down the Show-Me State’s sometimes-up-for-grabs 10 electoral votes. (The last Republican who carried the state of his convention was George Bush in 1992, when he was nominated for a second term in Houston.)

Whichever host committee wins will have to raise about $60 million in private money, because the government foots the bill for security but not much else. Charles and David Koch, the billionaire industrialist brothers from relatively nearby Wichita, Kan., can be counted on to provide just as much fundraising help as their fellow conservative bankroller Sheldon Adelson, the casino magnate central to the Las Vegas bid.

None of the three cities ready to organize viable bids for the Democratic National Convention offers the libertine enticements of Vegas. But each will similarly sell itself as a place to make sure a potentially competitive state stays blue. (Before last year, when Obama came up 2 points short in North Carolina, the Democratic nominee won his convention state in five straight elections.)

The most visible early push, on behalf of Philadelphia, has been orchestrated by Rep. Robert A. Brady, who’s not only a Pennsylvania congressman but the city’s party chairman. The others are Minneapolis, a DNC runner-up for 2012, and Milwaukee. Republicans routinely make presidential charges into Pennsylvania, Minnesota and Wisconsin, but all three have gone to Democrats in the past six national elections, and the party’s Electoral College algorithm counts on keeping it that way.

Two cities in solid blue states, Newark, N.J., and San Francisco, may also seek to woo the Democrats, and Charlotte is pondering a pitch to the Republicans. But logistical and political considerations make those very long shots, especially because there are a couple of big bidders preparing to woo both party’s site-selection committees.

Ohio is the epicenter of American presidential politics. Lesson No. 1 for sounding smart on the topic is that no Republican has ever been elected president without carrying the state, and the last Democrat to pull it off was John F. Kennedy. So it seems pretty obvious both parties will want to fall in love with one of two bids expected from the Buckeye State, which hasn’t hosted a convention since 1936.

Cleveland is the underdog here. While anchoring the most reliably blue part of the state, it’s come up short in four convention bids in the past 40 years, all while the region’s population has been in rapid decline. But Columbus, with a diversified and expanding economy, may soon anchor Ohio’s second-biggest metro area; already, the state capital region has become so much the bellwether center of the 20 electoral-vote state that it drew more than a dozen visits last fall from each national ticket.

Ohio State University offers an iconic football stadium in which to revive the tradition of the climactic outdoor acceptance speech. And the city is earning a decent reputation as a Midwestern oasis for hipsters and foodies.

Still, there are no croupiers or wedding chapels, bars close by 2:30 a.m. and the closest thing to in-your-face adult entertainment is the corporate headquarters of Victoria’s Secret.

There’s also no professional basketball team — a distinction with unique political importance next time around.

Republicans have all but officially decided to hold their convention the week before or the week after July 4, two months earlier than last time. The move is part of an effort to shorten the potential nastiness of the primary season (fewer debates are also part of the strategy) and to take fuller advantage of campaign finance law, which says only the formally nominated candidate may spend funds earmarked for the general election campaign.

Since the parties require unfettered access to their convention halls in the month beforehand, the new timetable could handicap RNC bids from Cleveland and longer-shots Dallas, Salt Lake City, Detroit and Indianapolis. That’s even though most of their NBA teams won’t have a genuine shot at needing their home courts for the 2016 finals. (The same requirement could help St. Louis, which looks to make a solid pitch, along with outside shot applicants Nashville and Phoenix.)

All those cities are also planning to woo the Democrats. They will have their convention after the Republicans — the last-word advantage customarily awarded to the party in the White House — but almost certainly before the summer Olympics open on Aug. 5 in Rio de Janeiro.

The Republican and Democratic national committees won’t formally put the conventions out to bid before January, and they’re unlikely to announce the winners before the midterm elections. So actual planning for summer fun in 2016 will have to wait a while.