A visit from Massachusetts Sen. Elizabeth WarrenElizabeth Ann WarrenGillibrand unveils bill to offer banking services at post offices Warren challenger sues to keep displaying 'fake Indian' signs Dems demand end to waivers used to pay people with disabilities below minimum wage MORE (D) would help any red state Democratic Senate candidate. But she's a liberal! But she's from Massachusetts! But she's an elitist Ivy League law professor! All of that is true, and none of it matters.

So far this election cycle, she has crisscrossed the U.S., stumping for liberal Democrats, but also going into areas that surprised some outside observers. She stumped for Alison Lundergan Grimes in Kentucky in Grimes's effort to unseat Senate Minority Leader Mitch McConnell (R). Warren visited West Virginia to assist West Virginia Secretary of State Natalie Tennant, who is running in the open seat to replace Sen. Jay Rockefeller (D).

Yes, a Massachusetts senator traveled to states that have been electing Republicans or moderate Democrats at the statewide level for years. It seems odd on the surface or a miscue from relatively inexperienced candidates, but in reality, it makes a lot of sense.

Why Warren works

First, Warren is an effective fundraiser. According to CBS News, through the end of June, Warren raised $2.3 million for fellow Democrats, and her fundraising schedule will continue through the fall. In a series of races that might be decided by single digits, Democrats, hoping to keep control of the U.S. Senate, can use all the funding they can get.

Second, Warren's appearances on behalf of Senate candidates (and incumbents seeking reelection) carries with it substantial media attention, especially as the Massachusetts senator's national profile builds. In fact, her appearances in red states likely draw even greater media attention that they do in deep blue states. Senate candidates, particularly challengers with less experience and lower name identification, benefit from that media attention, as it translates into free advertising. Every newspaper, every new radio station, every TV news broadcast in a state will flash that candidate's name across the screen when Warren comes to town.

Third, Warren asserts a populist message that can be crafted nicely to swing voters. She talks about big business, bankers, oil companies and others squeezing the little guy. She rails against an economic system rigged against the average American, and polling shows that Democrats and Republicans agree with her. She talks passionately about the American dream, about the challenges facing young people and about a blue collar America that many long to have back. She tells voters in a given state that they don't have to agree with her on every issue but argues that they can all agree that the economic recovery has left a lot of people behind. Independents and moderate Republicans might not like her views on social issues, but they are not finding many Republican candidates passionately telling them, "I feel your pain," either.

Fourth, beyond swing voters, 2014 is about a ground game and a turnout operation. Democrats who want to be successful need independents and need to convert some moderate Republicans, especially in red states. But Democrats need Democrats, too. The base must be mobilized; the base has to have passion; the base needs to feel like the race matters. A vocal, passionate progressive does that. Warren does that.

The risks of a Warren visit

Elizabeth Warren isn't a sure thing, as nothing and no one in politics is. There remains one argument that suggests she is a liability.

Some argue that a progressive like Warren holds very different values from voters in states like Kentucky and West Virginia. That is absolutely true on a host of issues. For example, both states, to different degrees, lie in coal country, and Warren's views on environmental regulation and the future of energy production are inconsistent with that of the coal industry. She acknowledges that she doesn't agree with the candidates for whom she is stumping on every issue. However, even on an issue like coal, Warren's populist message has resonance. Coal miners, in many ways, have been left behind by a changing economy. They have been taken advantage of by corporate executives over things like workplace safety. The message Warren delivers will enrage executives, but might well connect with those in the mines.

But candidates in these states are strengthened by pointing out that they don't agree with Warren on everything. She's a liberal; they are not. Warren will help candidates by saying: "Here is an independent voice, someone I won't agree with about everything, but the Democratic candidate is the better choice."

In an era of polarized political advertising, Warren will not be the reason a candidate is called a liberal. Every Democratic candidate across the country — regardless of who campaigns for them — is labeled "a liberal like President Obama." And frankly, if a voter has written off a Democratic candidate as a rubber stamp for the president, Warren won't help or hurt.

But at the end of the day, if a voter thinks Alison Lundergan Grimes or Natalie Tennant or Sen. Mary Landrieu (D-La.) or Sen. Mark Pryor (D-Ark.) will have the constitution to stand up and say "no" to the president of the United States on certain issues, the voter probably thinks they can also say "no" to a freshman senator from Massachusetts.

And those candidates would be foolish not to invite that freshman senator from Massachusetts to join them on the campaign trail.

Hudak is a fellow in Governance Studies at the Brookings Institution and managing editor of the FixGov blog.