When Rep. Ron Paul (R-Texas) announced his most recent run for the White House back in May 2011, MSNBC Host Chris Matthews pressed him on the extent of his libertarian convictions. Would he have opposed the landmark 1964 Civil Rights Act had he been in office when it was considered, Matthews wanted to know.

It was a hypothetical question and Paul gave a fairly broad answer, saying he appreciated the intent of the law but disagreed with the specific language on property rights.

Left unmentioned was that Paul had -- in more than a hypothetical sense -- already cast a vote on the famous bill. On June 24, 2004, the House of Representatives took up a resolution "recognizing and honoring the 40th anniversary of congressional passage of the Civil Rights Act of 1964." Four hundred and fourteen members voted yes, and 18 didn't show up to vote. Only one member said nay: Ron Paul.

Throughout his congressional tenure, Paul has built a reputation as a legislator who marches to his own distinctive drumbeat. He is a Republican by label, not in the fraternal meaning. Oftentimes, his voting habits leave him utterly isolated from the rest of his colleagues, Republicans and Democrats alike.

"Ron Paul was his own island," said one Republican leadership aide. "Leadership tried not to visit and rarely had to. Sometimes we sailed through."

Using C-SPAN's database, The Huffington Post examined all the nay votes Paul cast during his current stint in Congress, from 1997 to the present. (Paul served several terms in the 1970s and 80s, but the C-SPAN archive doesn't stretch back that far.) From there, we pulled out every instance in which the congressman was either alone in voting against a measure or one of just ten or fewer House members to do so. There were more than 675 such instances.

A close examination of those votes -- some of which were on repeat bills, others of which were simple procedural votes -- helps illustrate just what principles drive the man who could very well win the all-important 2012 Iowa caucuses. But it also underscores how the congressman's black-and-white worldview of federal politics has led him to vote against legislation on constitutional grounds even if he may personally back it, from funding for a Holocaust memorial to resources for anti-terrorism training to child abuse prevention legislation.

After casting that no vote in commemoration of the Civil Rights Act, Paul was cheered inside Libertarian circles. His former chief of staff, Lew Rockwell (who is believed to be the author of many of Paul's controversial newsletters) wrote an item on his website declaring that "only the heroic Ron Paul dissented" on the legislation. In mainstream GOP circles, however, Paul was an outcast. George W. Bush held a White House ceremony featuring many Republicans praising the bill's anniversary.

Three years later, a similar situation would unfold. On June 20, 2007, Paul was one of two members of the entire House of Representatives to vote against the "Emmett Till Unsolved Civil Rights Crime Act," a bill that authorized $100 million over ten years to investigate unresolved civil rights-era murders. Paul's campaign did not return a request for comment for this article. But it stands to reason that he agreed with the complaint lodged by the other dissenting member, Rep. Lynn Westmoreland (R-Ga.), who said he thought "federal and state law enforcement units" could handle those cases "where there are good leads on suspects."

Civil rights issues weren't the only areas where Paul was a man alone in Congress. On foreign policy matters, and those pertaining to Israel in particular, he has routinely isolated himself from all other lawmakers.

On July 30, 1997, Paul was the lone dissenter on a House-passed resolution titled "Expressing the sense of the Congress regarding the terrorist bombing in the Jerusalem market." Three-and-a-half years later, he was the lone dissenter on a House-passed resolution congratulating Ariel Sharon for his election as Israeli prime minister. In July 20, 2006, he was one of eight no votes on another House-passed resolution sponsored by now-Speaker John Boehner (R-Ohio) condemning terrorist attacks against Israel.

The list goes on.

Paul's supporters have long argued that his posture towards Israel is driven not out of some latent anti-Semitism, but conviction that U.S. policy in the Middle East is imbalanced and over-engaged. And, indeed, a look at other votes on Paul's resume shows that he's been an equal opportunity offender.

In February 2005, he was the only member in the House to vote against a resolution "commending the Palestinian people" for conducting a "free and fair" presidential election. During the height of the Green Revolution, Paul was the lone House member to vote against a resolution "expressing support for all Iranian citizens who embrace the values of freedom, human rights, civil liberties, and rule of law."

Even when the terrorist target was America, Paul played a stubborn role: On September 23, 1997, he was one of seven members voting against a motion to suspend the rules and pass the Oklahoma City National Memorial Act of 1997.

None of these votes had any real-world implications, save that they set Paul apart from his colleagues as an adherent to a strictly limited foreign policy. As a result, they rarely come up when discussion turns to his presidential aspirations. They represent, as one foreign policy operative who worked on U.S.-United Nations relations noted, "Ron Paul being Ron Paul." But not all of the congressman's no votes were on ceremonial matters.

On September 7, 2000, Paul was alone in his opposition to a bill exempting the U.S. Holocaust Memorial Museum from limits established during the previous year's budget. The bill ultimately became law.

On March 10, 1998, he was one of two House members to vote against a motion to suspend the rules and pass the Birth Defects Prevention Act, which promoted better data collection and sharing on the topic. The bill ultimately became law.

On November 4, 1997, he was one of two members to vote against a motion to suspend the rules and pass a bill that would "require the Attorney General to establish a program in local prisons to identify, prior to arraignment, criminal aliens and aliens who are unlawfully present in the United States." The bill ultimately became law.

On October 27, 2000, he was one of two votes against the Assistance for International Malaria Control Act. The bill, which was sponsored by former Sen. Jesse Helms, eventually became law.

On February 1, 2000, Paul was one of two no votes on a motion to suspend the rules and pass the Child Abuse Prevention and Enforcement Act, which provided more state grant funding for criminal justice and child welfare agencies to collect and share data on child abuse. The bill ultimately became law.

On December 15, 2009, Paul was the only member to vote against a motion to suspend the rules and pass the "First Responder Anti-Terrorism Training Resources Act" which loosened restrictions on the type of financial help the Department of Homeland Security could get for the purpose of terrorism preparedness and prevention. The bill ultimately became law.

Paul was one of only three House members to vote against a conference report creating a commission to investigate the 9/11 attacks. One of the other two to vote against the measure (which became law) is former Rep. Ray LaHood (R-Ill.), the current Secretary of Transportation.

On October 17, 2001, Paul was the lone no vote on a motion to suspend the rules and pass the Financial Anti-Terrorism Act of 2001, which dramatically heightened rules and enforcement on funds that went to terrorist or terrorist-connected organizations. The bill wouldn't become law but portions of it were put into the PATRIOT Act.

On November 8, 1999, Paul was the lone nay vote on a motion to suspend the rules and pass an amendment to fund the Office of Government Ethics.

On July 1, 2010, he was one of four members who voted against a motion to suspend the rules and pass an amendment that prohibited "any person from performing lobbying activities on behalf of a client which is determined by the Secretary of State to be a State sponsor of terrorism."

There are, of course, many more. Paul was one of two House members to vote against a September 2008 motion to adopt a bill extending a "grant program for armor vests for law enforcement officers." That same month, he was one of two members to vote against suspending a rule and adopting a bill that would require group health plans to ensure that inpatient coverage and radiation therapy were provided for breast cancer treatment.

Paul was the only member to vote against a House measure expressing condolences to the families and victims of the February 2010 Chilean earthquake. He was also the only member to vote against a House measure expressing condolences to the victims of the Haiti earthquake. And when the House considered a resolution that would make any organ donor eligible for a Stephanie Tubbs Jones Gift of Life medal, in honor of the late congresswoman, he was, once again, the lone vote in opposition.

All of these votes have explanations that Paul and his supporters have made in various forms throughout his rise on the national political scene. Usually, they boil down to a simple argument: the legislation is either antithetical to small government convictions or contradicts the text of the Constitution. Why, for instance, expand the Department of Homeland Security's capacity to accept gifts when the department should never have been created in the first place? Why give more money for malaria control in other countries when the United States has its own medical issues with which to contend.

But for Paul's critics -- Democrats and Republicans alike -- governance doesn't take place in such a confined vacuum. Moreover, they say, his voting record provides real-life proof of the turmoil that would result from his style of leadership if he were to become president.

"I never once saw him in the Speaker's Office, come out of the Leader's office or attend a Whip dinner," said a former GOP leadership aide, who worked with Paul in previous Congresses. "The guy marches to the beat of his own drum which was fine because there were enough conservative Democrats that we never needed his vote."

The aide emailed The Huffington Post minutes later: "Of course that quote will probably help him!"