(CNN) -- House Speaker Nancy Pelosi on Wednesday called on President-elect Barack Obama to govern from the middle, as her party sat poised to gain its widest House majority in 15 years.



House Speaker Nancy Pelosi, D-California, celebrates election victories Tuesday night in Washington.



According to projections, Democrats in the House were on track Wednesday to increase their majority by at least 18 seats, a margin that would give Obama a formidable tool to push his legislative agenda after his January 20 inauguration.



Democrats took at least 22 seats from Republicans in Tuesday's election, with the GOP taking four seats from the Democrats, according to CNN projections.



With winners yet to be called for eight of the House's 435 seats, Democrats were projected to win 254 seats, with Republicans having 173.



"I don't know what the final number will be," Pelosi said during a Wednesday afternoon news conference on Capitol Hill. "But it will be well over 250. It's a signal of the change that the American people want."



Pelosi, D-California, said she hoped Obama would "bring people together to reach consensus" on issues that concern Americans. "A new president must govern from the middle," she said.



Topping her agenda, she said, would be "growing the economy, expanding health care, ending dependence on foreign oil and ending the war in Iraq."



When he woke up Wednesday morning, Republican National Committee Chairman Mike Duncan said, he felt like the boy who stubbed his toe, the character in a quote from President Lincoln, who said: "It hurts too bad to laugh, and I'm too big to cry."



Duncan also called on the president-elect to govern from the center and warned that if Democrats moved too far to the left, Republicans could take back seats in the 2010 midterm elections.



"The last two times Democrats controlled the House, Senate and the presidency, they choked on the bone of responsibility," he said. "They lurched far to the left and introduced the country to President Ronald Reagan and Speaker Newt Gingrich."



Among Tuesday's GOP casualties was longtime Rep. Chris Shays of Connecticut, whose reputation for occasionally bucking his party couldn't keep him from losing to Democrat Jim Himes.



Shays' defeat leaves New England without any Republicans in the House. Shays was seeking his 11th full term.  Watch Pelosi say Americans voted for change »



Heading into Election Day, the Democrats had a 235-199 House majority. The Democrats' gains come two years after they took control of the House -- with a gain of 30 seats -- after 12 years in the minority.



Here are highlights of other races from Tuesday with projected winners:



Democrats gained at least two seats in Ohio, including that of Rep. Steve Chabot, who was seeking an eighth term in a Cincinnati-area district that normally votes about evenly for GOP and Democratic presidential candidates.



CNN projects that Chabot lost to Democrat Steve Driehaus. Just two years earlier, Chabot was re-elected with 52 percent of the vote despite an anti-Republican tide that helped Democrats capture Ohio's governorship and take a U.S. Senate seat.



Democrats also gained a seat left open by retiring Rep. Ralph Regula. Democrat John Boccieri defeated the GOP's Kirk Schuring in the northeastern Ohio contest.



• In New York, Democrats won three Republican seats, including two left open by incumbents not seeking re-election. In one of the open races, Democrat Mike McMahon won the last GOP-held seat in New York City, defeating the GOP's Robert Straniere. Democrat Dan Maffei defeated Republican Dale Sweetland, who was trying to win a seat vacated by 10-term GOP Rep. Jim Walsh.



In a rematch of a 2006 race, former naval officer Eric Massa beat GOP Rep. Randy Kuhl in a western New York district that generally votes Republican.



• Freshman Rep. Michele Bachmann, R-Minnesota, was projected to survive a race that tightened after she accused Obama of having "anti-American views." She was leading Democratic challenger
Who is the RNC chairman? What number of seats did house democrats take from the GOP? What do democratic wins signal? What did the RNC chairman warn Dems against? What did Pelosi say about the Dem victories? Who talked about what democratic victories signal? What did the House Speaker say about a new leader? What group chairman is warning democrats?
Mike Duncan four change that the American people want." if Democrats moved too far to the left, Republicans could take back seats in the 2010 midterm elections. "A new president must govern from the middle," Nancy Pelosi "A Republican National Committee
question: Who is the RNC chairman?, answer: Mike Duncan | question: What number of seats did house democrats take from the GOP?, answer: four | question: What do democratic wins signal?, answer: change that the American people want." | question: What did the RNC chairman warn Dems against?, answer: if Democrats moved too far to the left, Republicans could take back seats in the 2010 midterm elections. | question: What did Pelosi say about the Dem victories?, answer: "A new president must govern from the middle," | question: Who talked about what democratic victories signal?, answer: Nancy Pelosi | question: What did the House Speaker say about a new leader?, answer: "A | question: What group chairman is warning democrats?, answer: Republican National Committee