But Sanders, who has often been labeled a socialist, says that’s not an indication he’s ready to join the party.

“I am an Independent,” Sanders told The Hill. “Have been an Independent, will stay an Independent.”

“I think [this] presidential election is the most important in modern history for this country,” Sanders said. “We have now lived through eight years of the disastrous policies of one of the worst presidents in American history. … I think McCain in many ways is intending to follow in the policies of George W. Bush. I think that would be a disaster.”

For all his independence, Sanders caucuses with Senate Democrats and votes overwhelmingly with them. Yet he is attending his first convention after years of snubbing the big party when he served in the House.

He was elected to the Senate in 2006, a move that traditionally requires a broader political view to reach a larger voting bloc. However, Vermont has only one House district, and therefore Sanders is serving the same voters.

“I disagree with Democrats on many, many issues,” Sanders said. “My views haven’t changed. I have many disagreements with Obama.”

For Sanders, these points of disagreement are often more about emphasis than specific policies. Sanders has long believed that the party should do more to address economic inequality and ensure access to services like healthcare and education.

Some of his proposals fall to the left of centrist Democratic ideology. The senator has touted his adamant support for higher taxes on the wealthy, lower military spending and a single-payer national healthcare program. He has fought against trade agreements like NAFTA and opposed media conglomerates.

Though many of the senator’s traditional claims to independence from Democrats have stemmed from his democratic socialist philosophies, Sanders has also demonstrated a willingness to work with Republicans. His Low-Income Energy Assistance Program bill drew 13 Republican co-sponsors before being defeated last month.

“My style was to reach out and bring Democrats and Republicans together,” Sanders said of his time in the House. "In the Senate I’ve tried to do that as well … I am working with Republicans and will continue to work with Republicans on issues of mutual concern.”

Though Sanders steadfastly embraces his role as an Independent, he votes more loyally with the Democratic Party than do many Democrats. This Congress, the senator has voted with the majority of Democrats 95.4 percent of the time he’s cast a ballot.

That number also reflects a gradual increase from when Sanders was first elected to the House, in 1990. In his first two years, Sanders voted with Democrats 86.6 percent of the time.

Sanders suggested the increase was due more to the Republican Party becoming more conservative than to any change in personal loyalty.

“When he first entered Congress in 1991, the Democratic Party had a substantial number of 40 or 50 Southern members who were philosophically conservative,” said Garrison Nelson, a University of Vermont political science professor who has known Sanders throughout his time in office. “It’s a much different Democratic Party today than it was when Sanders first entered the Congress. It has moved in his direction. He hasn’t had to move in its direction.”

The last time Sanders voted against the majority of Democrats was in June, when he opposed ending debate on a rewrite of the Foreign Intelligence Surveillance Act.

Sanders has split with the party’s majority five of the 195 times he has voted this year.

But in several other cases, Sanders stuck with the majority of Democrats even when others split. In July, Sanders supported confirming the Bush-backed nomination of Gen. David Petraeus as new chief of U.S. Central Command. Only Sens. Robert Byrd (D-W.Va.) and Tom Harkin (D-Iowa) opposed the Petraeus confirmation, arguing against the management of the war in Iraq and the lack of focus on other regional issues.

In February, 11 Democrats balked at a Republican-sponsored initiative to prohibit funds directed toward the Indian Healthcare Improvement Act from being used to carry out anti-firearm programs. Sanders was not among them.

Eric Davis, a political science professor at Middlebury, said Sanders’s relationship with the Democratic Party has strengthened over time thanks to the party’s approach to his runs for reelection. The party stopped attempting to defeat Sanders’s bids, due both to his popularity and to his loyal voting record. In 2006, his campaign received money from the Democratic Senatorial Campaign Committee.

“Bernie has mellowed a little bit. He’s not as confrontational as he may have been 25 years ago,” Davis said.

“They may not have had his soul, but they had his vote,” Nelson added.