WASHINGTON — The Democratic Party seized control of the Senate in dramatic fashion in Tuesday's elections, achieving a 55-45 majority by capturing nine Senate seats held by Republicans and losing only one of their own.
The Democrats, who last controlled the Senate six years ago, reversed a 53-47 Republican majority despite an unprecedented campaign effort by President Reagan to stave off the Democratic challenge.
"If there was a Reagan revolution, it's over," claimed House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), who is retiring from Congress. O'Neill's House seat was won by Joseph P. Kennedy II, son of the late Sen. Robert F. Kennedy.
Outgoing Senate Majority Leader Bob Dole (R-Kan.) conceded that "it's going to make it more difficult for the President."
With Democratic voters turning out in unexpectedly large numbers, Republican incumbents in Alabama, Florida, Georgia, North Carolina, North Dakota, South Dakota and Washington all lost. In addition, Republican candidates seeking to retain seats vacated by retiring Republicans lost to Democrats in Maryland and Nevada.
Only in Missouri, where former Gov. Christopher S. Bond defeated Democratic Lt. Gov. Harriet Woods 53% to 47% in the race for the seat of retiring Sen. Thomas F. Eagleton, were the Republicans assured of winning a seat held by a Democrat.
In California, another state where Republicans had hoped to gain a seat, Democratic Sen. Alan Cranston defeated Rep. Ed Zschau. Democrats held on in Louisiana and won in Colorado, both states where Democratic incumbents chose not to run again.
Against the decidedly Democratic trend in the Senate, Republicans held their losses to a minimum in the House. Democrats held a 253-182 advantage before the election and were expected to gain six more seats by the time final returns were tabulated.
And in the governors' races, Republicans gained eight seats, barely short of the 10 they needed to command a majority for the first time since 1970. They scored particularly striking victories in the South, wresting control of governorships in Alabama, Florida, South Carolina and Texas.
But by taking control of the Senate, Democrats cast a cloud over President Reagan's last two years in office. Although Democratic leaders immediately pledged to work with the popular President, their new-found control of the Senate, coupled with their continuing dominance of the House, will make it more difficult for the President to work his will in Congress.
"We want to cooperate," said Senate Minority Leader Robert C. Byrd (D-W.Va.). But he warned that if Reagan failed to work with congressional Democrats to write trade and farm legislation, "we're going ahead and putting a bill on his desk anyway."
As returns and late projections trickled in at Republican National Committee headquarters, Chairman Frank J. Fahrenkopf Jr. tried to put the best face on what was turning into a severe setback in the Senate.
"We did well in the House, we did very well in the governorships, we did well in the state legislatures," he said. "If we don't keep the Senate, we're three for four and that isn't bad."
The Democratic victory was a stinging personal defeat for Reagan, who had put his prestige and popularity on the line by campaigning exhaustively for Republican Senate candidates. Traveling 25,000 miles in three weeks, he appealed to voters to cast a final ballot for him by electing candidates that would retain a Republican majority in the Senate.
At the urging of his close friend, Sen. Paul Laxalt, general chairman of the Republican National Committee and chairman of his two winning presidential campaigns, Reagan even made a final election eve visit to Nevada to try to save for the Republicans the Senate seat that Laxalt is vacating. But the effort went for naught as former Rep. Jim Santini lost to Democratic Rep. Harry Reid 51% to 45%.
Liberal Rep. Wyche Fowler Jr. of Atlanta, an opponent of Reagan's policies of financial support for the contras in Nicaragua, scored one of the more surprising Democratic victories. He upset Sen. Mack Mattingly 51% to 49%. Mattingly had held significant leads in polls throughout most of the campaign but called on Reagan for a final campaign boost in the last week before the election as polls showed Fowler closing the gap.
Other GOP-held seats captured by Democrats were:
--Florida. Gov. Bob Graham soundly defeated Sen. Paula Hawkins 55% to 45%.
--North Carolina. Former Gov. Terry Sanford, also a former president of Duke University, defeated Sen. James T. Broyhill, who was appointed to the seat earlier this year after the suicide of incumbent Republican John East. The margin was 52% to 48%.
--Maryland. Rep. Barbara A. Mikulski handily defeated Linda Chavez, 61% to 39%, for the seat of retiring Sen. Charles McC. Mathias Jr.