Former Iowa Gov. Tom Vilsack dropped his 2008 candidacy for president Friday amid tough Democratic competition and sagging fundraising and poll numbers.

Likening his campaign to an explorer's voyage, Vilsack called his short time in the spotlight "a great journey."

"The boat was at the dock. It was ready to be launched, and what would you do? Would you just simply walk away from it, or would you get in the boat and see where it took you? Well, we got in the boat. We took a great journey. But it's time to bring the boat back to the dock," Vilsack told a group of reporters gathered at a news conference.

"So today, I am announcing that we are ending this presidential campaign," Vilsack said.

He said that while he believed he was well-positioned with his message and personal history, the one thing that prevented him from continuing was a lack of money.

Vilsack left the governor's office in January but quickly faced a tough challenge from better-known rivals, namely New York Sen. Hillary Rodham Clinton and Illinois Sen. Barack Obama.

The latest Strategic Vision Iowa Poll released Thursday showed Vilsack running fourth in a poll of 600 among likely Iowa Democratic caucus-goers. In the Feb. 16-18 poll, Vilsack pulled 14 percent of poll participants, behind John Edwards' 24 percent and a tie between Clinton and Obama at 18 percent.

In that poll, Vilsack did better than other declared candidates including Delaware Sen. Joe Biden, New Mexico Gov. Bill Richardson, Connecticut Sen. Christopher Dodd, and Ohio Rep. Dennis Kucinich.

Vilsack was having difficulty raising the $20 million political experts estimate presidential candidates will need to have in hand by June 2007. Both Clinton and Obama are expected to raise between $75 million and $100 million in their bids for the nomination.

Vilsack, 55, cultivated a centrist image as governor, balancing the state's budget, resisting pressure to raise taxes and chairing the centrist Democratic Leadership Council. He also emphasized increased spending on such priorities as health care, education and economic development.

Beyond his record as governor, Vilsack tried to sell himself as a candidate with a compelling personal story, which he hoped would spark national interest in his candidacy. He was left as an infant at a Catholic orphanage in Pittsburgh and adopted by what he has described as a "troubled but loving family."

His adoptive parents were well-to-do and sent him to a private preparatory school, but his mother was an alcoholic who beat him and his father suffered trying financial reversals.

Vilsack managed to transcend his difficult childhood to build a successful career in law and politics. He met his wife Christie in college in New York and they settled in her hometown of Mount Pleasant — population 8,700 — after he graduated from law school. He joined his father-in-law's law practice.

Then, in 1986, a disgruntled citizen burst into a Mount Pleasant city council meeting and opened fire, killing Mayor Edd King. Vilsack was elected mayor and faced the task of healing the close-knit community.

He then won election to the state Senate, and won a long-shot bid for governor in 1998.

The Associated Press contributed to this report.