The fall campaign's messaging is set to get a mid-summer test drive.
Some of this year's most intriguing political story lines will converge on Tuesday, with contests in four states, plus a rare recess-interrupting House vote that will outline the stakes and obstacles for both parties this year.
The highest-profile action will come in the Colorado Senate race, where the favored choices of both party establishments are facing difficult fights against outsider candidates with insider-type resumes.
In most years, candidates like Democrat Sen. Michael Bennet and Republican former Lt. Gov. Jane Norton would be favored to glide to their parties' nominations, and would face off in a general election that could go either way.
But as we've learned over and over in 2010, this is not like most years.
President Obama's endorsement of Bennet hasn't scared Andrew Romanoff, a former state House speaker, out of a race that's grown increasingly bitter in its closing days. Romanoff has the backing of former President Bill Clinton, who's emerging as a bigger potential force for Democrats in critical districts than the current president.
On the Republican side, Norton is the latest establishment choice to feel the singe of the Tea Party crowd, which has coalesced around Ken Buck.
Buck, a county district attorney, has plenty of Washington support -- most notably that of Tea Party favorite Sen. Jim DeMint, R-S.C. -- but has an insurgent's energy heading into primary day.
Back in Washington, a key vote Tuesday could have even bigger implications in the battle for control of Congress this year.
House Speaker Nancy Pelosi is hauling her members back to the nation's capital just one week into the House's summer break. They'll be voting on only one substantive item -- a $26 billion package of aid to states that passed the Senate last week after weeks of delays.
The bill perfectly encapsulates the campaign messaging of both Democrats and Republicans this year. Democrats are touting the measure as a way to save the jobs of thousands of teachers and firefighters, plus to preserve critical services under state Medicaid programs.
To Republicans, the measure is emblematic of the culture of spending they're vowing to change. The cost of the measure is offset by budget cuts and closing tax loopholes, but GOP leaders relish the prospect of Democrats interrupting a congressional break to add more government spending.
The outcome of the measure isn't in doubt, with Democrats expected to support it overwhelmingly and send the bill on to the president for his signature. But the vote is likely to become a major campaign issue, illustrating either the critical services government provides, or the spending excesses of the federal government, depending on your political perspective.
Also on the calendar Tuesday: Sarah Palin's coattails get their latest test in Georgia, where the GOP gubernatorial run-off features the Palin-backed Karen Handel facing off against former Rep. Nathan Deal, who has the backing of the National Rifle Association.
Meanwhile, in Connecticut, the latest female CEO to vie for political office -- Linda McMahon -- looks to lock down the Republican nomination for Senate.