This is an archived article that was published on sltrib.com in 2016, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Republicans are confident that they'll retain control of the House of Representatives in November. That's because they're sure that Elbridge Gerry, who died more than two centuries ago, will be a more important factor than Donald Trump.

There's plenty of nervousness in party ranks over the chance that voters will punish Republican congressional candidates for their nominee. That might result in a late-breaking wave election in which Democrats could pick up the 30 seats they'd need to win control in the House.

House Speaker Paul Ryan was worried enough to tell his colleagues this week to protect themselves even if that meant renouncing support for Trump. A Wall Street Journal/NBC News poll added to Republican concerns when it showed a six-point public preference for Democrats in congressional elections. That's the minimum margin Democrats need to capture a majority; winning by three or four points nationwide won't do it.

That's where Elbridge Gerry comes in. He's remembered less as a signer of the Declaration of Independence, a governor of Massachusetts and James Madison's vice president than as the man who gave his name to the practice of manipulating legislative-district lines to favor the party in power. For 200 years, Democrats and Republicans have worshiped at the political altar of "gerrymandering." (Mander? The shape of a Massachusetts state senate district drawn in 1812 by Gerry's allies was thought to resemble a salamander.)

When Republicans swept the 2010 Congressional elections, they controlled most of the power to redistrict after the census of that year. A testament to their success is that by most estimates, fewer than 10 percent of the 435 House seats are even competitive this time.

Two examples illustrate the picture. In 2012, Barack Obama won a comfortable victory in Pennsylvania as did the Democratic senate candidate, Bob Casey. Yet Republicans won 13 of the 18 House seats in the state. Similarly, the top of the ticket in Michigan went strongly for the Democrats, but Republicans won nine of the 14 House districts.

Some of this is due to population patterns; Democrats are more bunched together in urban and suburban districts. But much of it reflects the way Republican state legislators drew friendly congressional lines.

"It's much harder to pick up 30 seats now then it was before the Republican gerrymandering after 2010," acknowledges Mark Gersh, the foremost Democratic expert on House races.

To see the difficulty, the Rothenberg-Gonzales Political Report, one of the best nonpartisan election analysts, currently rates only 36 of 435 congressional districts as competitive. Seven of those seats are held by Democrats, 29 by Republicans.

Therefore if Democrats hold all their current seats and win every one of the competitive Republican-held districts, they would still fall one seat shy of a majority.

That's why they'd need a late-breaking wave in which Hillary Clinton wins by a double-digit margin with some demoralized Republicans staying home and angry Trump voters punishing down-ballot Republicans.

The likelihood of that occurring is thought to be around 25 percent. But Democrats were cheered by the six-point advantage in the congressional horse race that the Wall Street Journal/NBC News poll showed, and a 10-point margin in a Reuters survey.

For now, the odds favor Ryan. He's likely to remain speaker, though with a reduced majority. If, however, Democrats can build on their advantage over the next three weeks, a Democratic majority could be within reach. It's Trump versus Gerry.