The road to the 2016 presidential election begins with the Iowa caucuses, and Hillary Clinton has been securing a lead against potential Republican candidates in new polling data.

The Des Moines Register and Bloomberg Politics Iowa poll found Clinton leading against six GOP politicians, but one former Republican presidential candidate proved to challenge the former U.S. Secretary of State. Of the seven potential Republican presidential candidates, former Massachusetts Gov. Mitt Romney was the only GOP name to defeat Clinton, although it was by 1 percentage point. Romney received 44 percent to Clinton's 43 percent.

Rep. Paul Ryan, R-Wis., Romney's 2012 vice presidential candidate, also presented a challenge for Clinton, but the former New York Senator beat him out by 1 percentage point. Iowans favored Clinton with 44 percent to Ryan's 43 percent.

Clinton maintained her lead against Sen. Rand Paul, R-Ky. Clinton garnered 44 percent, while Paul received 41 percent of the poll.

New Jersey Gov. Christie has been another potential name for the Republican presidential ticket. Christie, however, received 38 percent of the poll against Clinton's 43 percent.

Former Florida Gov. Jeb Bush has been actively campaigning for House of Representative and Senate candidates ahead of the midterm election. Bush has been another name to potential campaign against Clinton's likely campaign. Among Iowan voters, Clinton would still defeat Bush with 46 percent to 39 percent.

Sen. Marco Rubio, R-Fla., and Sen. Ted Cruz, R-Texas, fared no better against Clinton. Against each of the two Republican Senators, Clinton received 45 percent, while Rubio attracted 37 percent and Cruz swayed 35 percent of the survey.

Among Iowa Democrats, Clinton overwhelmingly is the first choice as the Democratic Party's candidate. Clinton received 53 percent of the "First Choice" questionnaire, while Sen. Elizabeth Warren, D-Mass., was the only other name to receive double digits, 10 percent. Vice President Joe Biden was the third most popular first choice.

When Iowa Democrats were asked for their "Second Choice," current Secretary of State John Kerry was the preferred choice with 21 percent. Biden followed with 19 percent ahead of Clinton and Warren, tied with 15 percent.

Biden, Clinton and Kerry also have a high favorable rating, while Warren's name recognition didn't immediately sway voters. Clinton's favorability rating was 76 percent and 60 percent for Biden and Kerry, each. Warren received a favorable rating of 44 percent but a "not sure" rate of 45 percent. Biden, Clinton and Kerry's "not sure" rating were in single digits. Coincidentally, Warren is scheduled to visit Iowa to campaign for U.S. Senate candidate Bruce Braley.

The Des Moines Register and Bloomberg Politics poll was conducted between Oct. 1-7, with 851 registered Iowa voters who will "definitely or probably will attend" the 2016 caucuses.