The Iowa caucus is a week away, and polling shows a tight, four-way race between Senator Bernie Sanders, Senator Elizabeth Warren, Mayor Pete Buttigieg, and former Vice-President Joe Biden. As the first primary, Iowa plays a big role in creating narratives and can give candidates a boost to New Hampshire and South Carolina.

The Democratic primary in 2004 has some similarities to the current situation. There was a polarizing incumbent, George W. Bush, and no clear frontrunner in the race to face him. Senator John Kerry was in the middle of the pack until the final week when he started to climb and unexpectedly won. He rode this momentum to win New Hampshire and build a comfortable lead over his closest rivals.

Moderate Muddle

Therefore, Senator Sanders' momentum into the final week is an encouraging sign for his campaign. Another positive is that the "moderate" lane is clogged, while he and Senator Warren are the only two candidates in the more "liberal" lane. In an ordinary primary, this would be a liability, since it puts a natural limit on his support and appeal. And, it's certainly possible that it could hurt him in a general election in terms of winning voters who are anti-Trump but may not be receptive to a socialist message.

Some of the occupants clogging the "moderate" lane include the current frontrunner, former Vice-President Joe Biden, former NYC mayor Michael Bloomberg, Senator Amy Klobuchar, and Mayor Pete Buttigieg. The longer each one of these candidates stays in, the better Senators Sanders chances get to win the nomination. Of the moderates, Klobuchar is the weakest but also has some momentum going into Iowa as the latest polling shows her rising to third place. Her entire candidacy rests on Iowa, but if she breaks through, it could mean she will be able to stay in the race for another couple of months.

Despite Bloomberg's dramatic, late entry into the race, he's failing to catch on and isn't even listed on many early primary ballots. Unfortunately for the other moderates, Bloomberg has the financial assets to stay in the race and drive up the price of advertising inventory and staffers. Although it doesn't seem likely that he can win, he can dent the margins and win support from the other moderate candidates.

For a small-town, 37-year-old mayor who failed in his bid to become the DNC chair, Mayor Buttigieg is outperforming his and anyone else's expectations by a significant margin. He has also proven himself to be an adept fundraiser, giving him the resources to stay in the race. His chances to secure the nomination remain slim but he's certainly carved out a political future for himself.

Biden is the clear frontrunner and has basically been in first place the entire race. He appeals to African-American voters and the white working class. He has some serious vulnerabilities including his record which was left-of-center at the time but now looks conservative by today's standards. Additionally in public, he seems to continually be on the verge of making a verbal gaffe. Further his election and the legislative record doesn't engender confidence given flameouts in the 1988 and 2008 Democratic primaries. He seems to have a fondness for bipartisan-ship which simply isn't consistent with Republican obstructionism during the Obama and Trump eras.

Sanders' Strength

The state of the race is benefitting Bernie. While the moderates fight over 60% of the Democratic primary, he is winning over 40% of the "liberal" lane. His ground game and enthusiasm is unparalleled. For example this past weekend, his volunteers knocked on 100,000 doors which is particularly impressive given that 171,000 people participated in the 2016 DNC Iowa caucus.