How are House and Senate candidates’ war-chests faring this election cycle? The animations below show who has been pulling further ahead, and who has been closing fund-raising gaps as the races mature.

Itemized contributions, which are reported to the FEC along with the date the contributions were made, have allowed us to reconstruct a detailed accounting of the funds available to candidates over time. Beginning with the first quarter of 2011, we looked at all itemized contributions made to candidates in competitive races (rated by Cook as Likely, Lean or Toss up within the last month) reported to the FEC up through the end of the second quarter of this year (the most recent filing deadline). This does not include Independent Expenditures supporting or opposing candidates by outside groups, nor “dark money” expenditures from 501 (c) organizations like Crossroads GPS.

These animations show the evolving status of the funding landscape in competitive Senate and House races through the second quarter of 2012. The Democratic funding advantage is displayed on the y-axis; bars with positive values indicate that the Democratic candidate leads in fund-raising, while a negative value indicates that the Republican candidate leads. Races are colored according to the party which previously held the senate seat, either as an incumbent running in this cycle or a retiring senator.

Money in Senate races over time:

The time series animation above highlights a few trends. The first is that the party that currently controls the seat tends to lead in funding. This is unsurprising, given incumbents’ inherent fund-raising advantages. North Dakota and Hawaii are interesting exceptions to this. (Races can be highlighted by clicking their check-box on the right of the graph.) A partial explanation is that both races are for open seats. So current democratic candidates do not benefit from true incumbency advantages in fund-raising potential.

Another notable pattern we see is that challengers who join the race later tend to fund-raise faster than the incumbent once they join the race. Massachusetts is a particularly strong example of this effect, where Democratic challenger Elizabeth Warren got into the race comparatively late, but once she did, she caught up with incumbent Senator Scott Brown (R) quickly. This also occurred somewhat in Virginia, Hawaii, Ohio and Nebraska.

Below is a similar time-series chart for competitive House races. This graphic also displays the Democratic funding advantage in each race, based on itemized contributions reported to the FEC through the second quarter of 2012. Once again color of the bar indicates which party controlled the seat in the prior Congress. New seats created by redistricting in which neither party has historical control are denoted by green.

Money in House races over time:

The major trend visible above is that in House races, funding gaps between parties seem to grow over time. Once again, candidates trying to hold a seat (e.g. a democrat running in a district in which the seat was controlled by the democratic party in the last cycle) tend to do better in terms of fund-raising than candidates trying to flip a seat.

This effect is not determinative in all cases, however. In in the AR-04, AZ-01, CA-09, CA-47, IN-02, MD-06, NC-13, and the OK-02 candidates challenging for a seat previously held by the opposing party are out performing the candidate from the incumbent party.

We also see a “rebound effect” similar to what was observed in the Senate races, in which money comes in faster later on to overcome initial leads in some of the races. The FL-22, IL-08, MA-06, NC-08, and the NV-03 are all interesting to watch in this regard.

As these races continue and more data is available, graphics of this kind will become increasingly informative. Ultimately we will be able to pair this time-series funding data with time-series polling. This will provide a window into how changes in funding advantages and changes in polling leads are correlated.