ALLENTOWN — Charlie Dent has been the Floyd Mayweather Jr. of Pennsylvania's 15th Congressional District.
Like the undefeated boxer, Dent came out on top no matter the challenger or the political climate during the last 14 years.
Opposed by the well-heeled and popular Democrat John Callahan in 2010, Dent dispatched him by 15 points. Running against Democratic enthusiasm galvanized by Barack Obama's message of "hope and change" in 2008, he cruised to victory by 17 points.
Dent was viewed as so strong, no one even challenged him in 2014.
But Dent's decision not to seek re-election in 2018 created a political vacuum attracting contenders from both sides of the aisle. At least six Democrats and four Republicans said they intend to run.
A Democrat hasn't represented the district this century, but the party appears energized to combat President Trump and added the Republican-leaning district to their list of "battleground races" next year.
That has the political world asking if the 15th District, centered in the Lehigh Valley but stretching from the Delaware to the Susquehanna Rivers, is truly up for grabs.
"If I'm a Republican and I'm looking at all these signs, there is a real concern that next November the Democrats could win the House," said Chris Borick, a political scientist at Muhlenberg College. "Circumstances are falling into place to make districts like the 15th — a competitive district that is a bit of a reach for Democrats — a way to get that majority."
In the last half of the 20th century, the parties passed power back and forth in the 15th District, but Republicans have held the seat for the last 19 years. Paul McHale, who served from 1993 to 1998, was the last Democrat in the seat.
Analysis of voting patterns by Roll Call and the Cook Political Report show the district leans Republican, but voter registration statistics give Democrats a slight lead.
There are 199,858 Democrats and 185,491 Republicans in the district, but there also 76,902 voters registered to other parties or as independents, a mid-December report by the Pennsylvania Department of State shows.
The district has been considered a moderate one, voting for Democrat Obama in 2008, and for Republicans Mitt Romney in 2012 and Trump in 2016.
It three times elected fiscal conservative Republican Pat Toomey, who's now in the Senate, and then moderate Dent, who consistently attracted crossover support from Democrats and independents. Dent now brands the district, which was realigned after the 2010 census, as "center right."
Redistricting solidified Dent's dominance in 2012, when the 15th lost some of its Democratic neighborhoods in Easton and gained a constituency with a more Republican voting record in Dauphin, Lebanon and Berks Counties.
The district showed signs of being a low priority for Democrats after the redistricting: Callahan raised $2 million to Dent's $2.4 million in 2010; the subsequent Democratic challenger didn't break $50,000.
The Cook Political Report ranks the 15th as one of four in the state that "leans Republican," with a partisan voter index of plus-4 based on its performance during the last two presidential races. The higher the number, the more the district leans. Districts that are true tossups, Borick said, usually run a plus-1 or plus-2 rating.
In districts with a plus-5 index, the incumbent wins about 77 percent of the time, even against political headwinds, Cook says. But when that incumbent retires, his or her party's retention rate for the seat falls to 31 percent.
Midterm elections can be tough for the president's party, and indications are that historic trend could be amplified under Trump. Special counsel Robert Mueller's investigation into Russian interference in last year's election has dogged Trump's administration. It's unclear what impact the GOP tax overhaul — a major legislative victory for the president — will have. Trump's style and policy are causing waves even in his own party.
A potential voter backlash shows up in polls measuring whether voters are more likely to vote for an unnamed Democrat or Republican in the congressional election. Real Clear Politics, which averages those "generic" polls, shows Democrats enjoy a 13 percent advantage across the country.
"Democrats have the decided edge in terms of excitement. Maybe the most important element in the election in the 15th District, other than the candidate themselves and the baggage they bring, … will be the excitement of the voters," said G. Terry Madonna, a political scientist at Franklin and Marshall College. "It's a referendum on Trump."
"I think when you have a Republican agenda that is this unpopular, including the tax bill, and an inability to get things done and you couple that with the Democratic energy, it is fertile ground" for Democrats, said Evan Lukaske, a spokesman for the Democratic Congressional Committee.
Of the 91 House districts identified as Democratic battlegrounds in 2018, the president won 68.
Republicans said their big tax victory and strong GOP candidates emerging to replace Dent will sway voters in the 15th District. Chris Martin, a spokesman for the Republican National Congressional Committee, said the GOP is delivering middle-class tax relief for the first time in 30 years, "while Nancy Pelosi is doing everything in her power to preserve the failed status quo."
Borick said the key will be whether the competitive primaries will push candidates too far right or left for the moderate district.
Apart from tax reform, Lee Snover, chairwoman of the Northampton County Republicans, expects GOP congressional candidates to campaign on immigration and the affordability of health care. To tackle those issues, she said, the Republicans need to put out a "good, clean candidate." And she sees that in the current field.
"We have to be very cautious in the primary not to destroy our candidates, not to eat our own," Snover said. "We have four strong, good candidates and let the best one win. We have to be unified to take on the Democrats."
Walter Felton, chairman of the Lehigh County Democrats, said he is impressed with the candidates expressing interest. He said Democrats are energized, citing last month's Northampton and Lehigh county executive races among others.
"We take every seat seriously," Felton said, "but this could be a really good year."
Madonna said the 15th District race is shaping up to be one to watch.