Republicans are clearly in a "Political Bull Market"
Republicans can clearly tell that they are in a "political bull market." So many Republicans are eager to run because the wind is clearly at their back. Republicans did not appear this strong in 1994 until July and did not appear this strong in 1980 until October. I dare say voters have never been so eager to vote against Democrats. Not since 1946 at least has the political climate been so anti-Democrat/pro-Republican.
Charlie Cook says it is difficult to see any scenario in which the Democrats do not lose the house. Numerous Congressional Democrats have announced retirement rather than run in 2010 (whereas most Republican open seats are open because the incumbents are seeking higher office statewide).
Just to quantify where we are: Intrade puts the 50/50 at Republicans gaining at least 35 seats in the House and holding at least 48 seats in the Senate. The contracts for Republicans holding at least 46, 47, 48, 49, 50, and 51 senate seats have all seen appreciation recently. (and this is before the filing deadlines in most states. many strong candidates may be yet to announce or at least yet to be nominated by a united party.)
But even those numbers for the senate as a whole understate the danger for incumbent Democrats. When individual races are rated, Republicans are the favorites in 8 races: AR, CO, DE, IL, IN, NV, ND, PA. That's 49. In WI and CA, the Republican is given at least a 45% chance. In NY and WA, the Republican is given a 35% chance. 53 Republican seats in 2010 is not out of the question -- with further gains likely in 2012 and 2014.
In the house, Republicans may reasonably gain 63 seats. http://www.marstonchronicles.info/index.php?option=com_content&task=view&id=308&Itemid=1144%20for%20a%20list%20by%20state.
Republicans also stand to gain 15-20 more house seats in 2012 just from the favorable demographic trends that are expected to be revealed in the next census.
The probability of victory for Republican candidates is high and so is the probability that Republicans will have a majority, likely in both houses.
There is still work to be done, but this is a truly prosperous time to be advocating for liberty. I recommend this concise book on persuasion techniques when advocating for liberty: "The Secrets of Libertarian Persuasion". Available at: http://www.theadvocates.org/secrets.html