The presidential primary campaigns, which have been increasing in momentum for more than a year, come to their conclusions in Arizona on Tuesday, when voters cast votes in one of more than 20 state contests nationwide.
Arizona voters have been taking a sophisticated approach to the election, political analysts said.
"The real challenge for the candidates is to figure out how to become more than uni-dimensional," said Earl de Berge, research director for Phoenix-based Behavior Research Center, which conducted the Rocky Mountain Poll.
"Voters are basically saying, 'Look, you can't pull me in on one issue. You're going to have to have good answers on a set of issues for me to feel comfortable with you,' " he said.
Among the top issues in Arizona during the campaign: immigration, the Iraq war, the economy, health care, education, energy, the environment and privacy rights.
The candidates generally have used their stump speeches in Arizona to outline their policy positions on a laundry list of issues.
Candidates in both parties also have been testing their messages here for November's general election.
Political strategists in both major parties agree that Arizona no longer is the rubber stamp for Republican candidates that it once was.
Consider this: Arizona has a Democratic governor, but a Republican majority in the Legislature.
The state's two U.S. senators, John McCain and Jon Kyl, are Republicans, but the state's eight U.S. representatives are split 4-4 among Republicans and Democrats.
Political strategists say that the continuing influx of new residents from Democratic-leaning California and Illinois, plus a surge of independent voters, makes the state more difficult to call. President Bush has turned off a certain number of Republicans, as well.
"The Western states - and Arizona certainly is in that bucket - are changing," de Berge said. "Fundamentally, they're becoming more competitive, less Republican, more centralist in their voting. As such, they're bellwether states this year."
Republican presidential hopefuls McCain and Mitt Romney built campaign infrastructures of staffers and volunteers in Arizona, while Democratic challengers Hillary Rodham Clinton and Barack Obama have upped that.
The Democrats both built campaign networks and opened campaign offices in the state.
Furthermore, all four of the major candidates also have picked up and flaunted endorsements from high-profile state political figures. All of those factors will come into play during the general election for the candidates who win their parties' nominations.
De Berge said, "All these guys can see that this is going to be a close election. There is a lot of money flowing in, which allows them to do a lot of advertising in every state. They think they can win Arizona. It's clear from the data that we rolled out the other day that this is becoming more combative here. So they've got to weigh in. They just don't have any choice."
Political analyst Mike O'Neil, president of public opinion research firm O'Neil Associates in Tempe, said the dynamics of the races could produce split results in voter turnout in Arizona - a decrease among Republicans and an increase among Democrats.
An expected landslide victory by McCain, plus McCain's shaky standing among conservatives, could turn off a fair amount of GOP voters, he said.
"I haven't seen anything other than to suggest that he's going to have a huge victory," O'Neil said. "It could actually depress things. Any race in which people feel it could be a foregone conclusion, it tends to depress things."
The best evidence of a coming avalanche victory for McCain is that none of the Republican candidates has stepped foot in Arizona since last week's primary election - a McCain victory - in Florida.
Furthermore, social conservatives, who may be more likely to side with Romney or Huckabee if it appeared to be shaping up as a close race, may just boycott the election altogether.
In contrast, the Democratic candidates have been charging up the electorate, which could produce a spike in voting, O'Neil said.
While Clinton leads Obama both nationally and in Arizona, Obama has been narrowing the gap.