Sinclair Broadcast Group, one of the nation's largest local TV station operators, will pay about $3.9 billion for Tribune Media, adding more than 40 stations including KTLA in Los Angeles, WPIX in New York and WGN in Chicago. (Steve Ruark/AP)

Sinclair Broadcast Group, the family-controlled TV station company headquartered outside Baltimore, wants to go from big to gigantic.

With its $3.9 billion bid for Tribune Media on Monday, Sinclair aims to add dozens of big-city stations — in Chicago, Los Angeles and Dallas, among other cities — to an already bulging portfolio that includes 173 mostly small-city stations.

What to expect when, or if, Sinclair finally swallows Tribune?

Sinclair showed what might happen the last time it took over a station in a large metropolitan area — WJLA, the ABC affiliate in Washington. In 2014, Sinclair completed its $985 million purchase of eight stations owned by Allbritton Communications, including WJLA-TV, which is now the largest Sinclair owns.

Sinclair has effectively remade WJLA in its own image, which is to say it continues to cover local and national news but with a distinctively conservative flavor.

Sinclair has been criticized for using its many stations to push Republican presidential candidates since at least 2004 when it announced it would air a documentary critical of Democratic candidate John F. Kerry but backed down amid pressure. It drew criticism from Democrats on the eve of the 2012 election when its stations in several battleground states aired a half-hour news “special” that faulted President Obama for his handling of the economy, his signature health-care law and the terrorist attack on a U.S. installation in Benghazi, Libya.

The company, which is controlled by David Smith and his three brothers, quickly drew WJLA to the right after purchasing it.

In the most recent campaign, WJLA, and Sinclair stations around the country, gave a disproportionate amount of neutral or favorable coverage to candidate Donald Trump compared with his rival, Hillary Clinton, according to internal documents supplied by people at WJLA. Sinclair officials pointed out that Trump and his surrogates were far more accessible to Sinclair’s reporters than Clinton.

Among the stories that Sinclair’s managers ordered stations to air were those questioning Clinton’s handling of her controversial email server, the documents show. Another “must-run” report — about her health — included this internal description: “Why did Hillary Clinton struggle with disclosing her medical diagnosis? She has been repeatedly faced with previous questions of trust. Can a president lead with so many questions of transparency and trust?”

There were no equivalent “must-run” stories examining Trump’s refusal to release his medical, draft or tax records, or the immigration records of his wife, Melania. But there was a story titled “Donald Trump Reflections of 9/11,” and a feature about women who were campaigning for Trump that included an interview with his daughter-in-law Lara.

Since its purchase of WJLA, Sinclair has added commentaries from Mark Hyman, a Sinclair executive and conservative pundit who also appears on many Sinclair-owned stations. During the campaign, Hyman regularly criticized Clinton and praised Trump. “Most Americans know very little about the leaked Clinton emails,” he said in one such commentary during the campaign’s waning days. “Major news organizations buried the most damaging. So we’re sharing some with you.”

The company has also added regular public-affairs programs produced from Washington and hosted by conservatives Sharyl Attkisson and Armstrong Williams, who served as Ben Carson’s business manager during Carson’s presidential campaign. Williams and Sinclair are business partners; in 2013, he acquired TV stations from Sinclair when the company reached federal limits on station ownership.

Since Sinclair’s acquisition of WJLA, many of its best-known reporters and journalists have left or not had their contracts renewed, including veteran anchors Gordon Peterson, Maureen Bunyan and Leon Harris, sportscaster Tim Brant and entertainment reporter Arch Campbell.

Sinclair said it was remaking the station’s newscasts to boost ratings. But the exodus of older journalists — Peterson and Bunyan had been on the air in Washington for more than 85 years, collectively — left some bitter afternotes. “After taking a hard look at Sinclair Broadcasting,” Peterson said in January, “I concluded that I would not be comfortable working in the new environment.”

In one of its more partisan efforts, Sinclair in 2012 commissioned a series of robo-calls to Maryland households that were voiced by Jeff Barnd, then an anchor with Sinclair-owned WBFF-TV in Baltimore and now the company’s national correspondent. The calls asked residents for their views on Lyme disease and same-sex marriage before asking recipients questions that were critical of Maryland’s then-governor, Democrat Martin O’Malley. A company executive told the Baltimore Sun that the questions were “straightforward.”

Despite much speculation, Sinclair hasn’t used Washington’s NewsChannel 8 (acquired in the Allbritton deal) as the platform for a national cable news channel, as some news sources predicted it would. But it has experimented with uniting its far-flung stations into a de facto news network. In 2003, it tried producing a common newscast from its Hunt Valley, Md., headquarters called “News Central” that was carried by many of its stations. The effort was later abandoned.

Sinclair has made no effort to revive the idea since then. But thanks to aggressive dealmaking, the company is now many times larger, and currently reaches viewers in 81 metropolitan areas. If it completes its deal for Tribune, it will reach nearly 70 percent of all television households.