As the presidential nominating process has evolved, voters in early primary and caucus states have grown accustomed to meeting candidates in living rooms and coffee shops -- intimate settings that facilitate personal connections.

But the presence of candidates with considerable national buzz and name-recognition -- most notably, Sens. Hillary Clinton, D-N.Y., and Barack Obama, D-Ill. -- has changed the tenor of campaigning in Iowa and early primary states. While in the past lesser-known candidates may have built up their bases by 30 or 40 activists at a time, Clinton and Obama have been holding larger rallies that have attracted as many as 1,000 to 3,000 people.

Political observers who look to states such as Iowa to reveal the true nature of candidates are concerned about this new trend. David Redlawsk, an associate professor of political science at the University of Iowa, said that once candidates "get in a bubble," they usually never get out again.

"It risks destroying the personal connection of the hallmark that is the Iowa caucus process," Redlawsk said.

Perceived second-tier candidates, however, are still campaigning in smaller venues. The advantage of that strategy, Redlawsk said, is that with the 50 people in a backyard, "you can bet most will show up to the caucus." The candidate will likely also walk away from such meetings with a sense of who the voters are.

On the Republican side, the dynamics of the Ames straw poll -- and the absence of three major candidates from the competition surrounding it -- have turned Iowa into a battleground of the lesser-known candidates. For most of June, July, and early August, Sen. Sam Brownback, R-Kan., Rep. Tom Tancredo, R-Colo., and Govs. Mike Huckabee and Tommy Thompson have crisscrossed the state and courted potential supporters in small groups.

John Rankin, Brownback's Iowa communications director, said that many one-on-one conversations with voters can go a longer way than one big event. He added that the Brownback campaign gets a strong response as it makes a point of traveling to small towns such as Iowa Falls -- population 5,193 -- in addition to more populous places like Des Moines.

"In Iowa, activists expect direct, one-on-one attention from candidates," Rankin said.

For former Massachusetts Gov. Mitt Romney, the expected straw poll win could contribute significant excitement to his already-ascending status as a front-runner. But while some of the 200 Romney events in Iowa so far this year have attracted as many as 400 to 500 people, he is still committed to meeting voters in groups as small as 20 people.

"What Governor Romney likes about the process in Iowa and New Hampshire is that the people insist on meeting the governor personally. These are relatively small states population-wise, and the people who live there are very good at making a personal evaluation of the heart and character of the candidates who are running," said Eric Fehrnstrom, a spokesman and senior adviser on the Romney campaign.

It will be particularly important for Republicans to continue to campaign in front of small crowds in restaurants and living rooms because the field is still taking shape and caucus-goers' commitments are not yet completely in a lock. A University of Iowa poll released in early August, which Redlawsk directed, found that just 20.5 percent of Romney supporters said they would not change their minds before the caucuses. Although Romney was ahead of other Republican candidates in the poll, Redlawsk noted that the most popular response to the question of who Republican voters support is still "I don't know."

"While Romney seems to be building a sense of inevitability, he's still got the problem that the Republicans are very unsettled," Redlawsk said.

The second-tier GOP candidates are aware both of the possible opening in the Republican field and of the importance of grassroots campaigning. Tancredo has discussed his immigration-dominated platform over the past few weeks in Iowa at places such as the Highland Elk in Perry and the Farmer's Kitchen in Atlantic. Thompson scheduled a Winnebago tour of all of Iowa's 99 counties leading up to the straw poll. Huckabee, who tied Sen. John McCain, R-Ariz., in an early August ABC News-Washington Post poll, has appeared at churches and picnics.

At the same time, the absence of 1,000-person rallies on the Republican side raises questions about the popularity of the Democratic Party over Republican candidates at this stage in the presidential race. Mary Tiffany, communications director for the Republican Party of Iowa, said that support among the state's activists for Republican candidates is more evenly distributed over a crowded field than on the Democratic side, which at this point is dominated by Clinton and Obama.

"The spread isn't as wide in the polls between the second tier and top tiers. Each candidate has good allegiance to them, and that will change over time eventually as the field winnows, and as more people get engaged," Tiffany said.

As the candidate fields tighten and caucus time grows closer, 1,000-person rallies become a way to show off widespread support. For now, candidates remain cognizant that face-to-face contact with activists is the most effective method of persuasion -- even Obama and Clinton have been mixing in the more intimate meetings with the large, showy events.

"It's not the same as getting 30 committed people in a living room who say, 'Now I'm going to knock on doors for you,'" Redlawsk said.

-- By Annie Shuppy for the Online NewsHour