(CNN) - A day ahead of Mitt Romney's return to New Hampshire, a poll showed the likely GOP nominee trailing President Barack Obama by a nine-point margin in the Granite State.
The survey, from WMUR and the University of New Hampshire, showed 51% of New Hampshire adults backing Obama and 42% supporting Romney. Five percent said they had not yet decided who to support in November's general election.
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Romney, who served as governor of neighboring Massachusetts from 2003 to 2007 and owns a vacation home on Lake Winnipesaukee, spent a considerable amount of time in New Hampshire ahead of the state's first-in-the-nation primary in January. He won the contest with 39% of the vote.
In WMUR/UNH surveys taken in the summer and fall of 2011, Romney led Obama by as much as eight points, but in February the trend began to shift, with Obama besting the Republican candidate for the first time in a year.
"The Republican nomination process has weakened Romney in his backyard," said Andrew Smith, director of the UNH Survey Center.. "He will have to consolidate support in New Hampshire and other battleground states if he hopes to defeat Obama in November."
Independents, traditionally a large and important bloc in the Granite State, broke for Obama in Monday's poll, with 40% supporting the incumbent Democrat compared to 35% for Romney.
On Tuesday, Romney will visit New Hampshire for an event his campaign is calling "A Better America Begins Tonight." Romney will be in the state as votes from five states - Pennsylvania, New York, Connecticut, Delaware, and Rhode Island - are counted and announced.
The Granite State was Romney's first victory this year after he lost the first contest, Iowa, by a slim margin to Rick Santorum.
In 2008, Obama won New Hampshire by a nine-point margin, beating Arizona Sen. John McCain 54% to 45%. The state, which was once considered to be solidly Republican territory, also went Democrat in 2004, voting for Sen. John Kerry by a narrow margin.
The WMUR/UNH poll was taken by telephone from 538 adults between April 9-20. The sampling error was plus or minus 4.2 percentage points.