Two Weeks Hence . . .

This post combines and updates the analyses and forecasts I presented in “Three Weeks Hence . . .” and “Another Election Indicator.”

As of today (UPDATED 10/23/10):

• The GOP will gain 8 Senate seats, leaving the Democrats with a 51-49 majority in the Senate. (This estimate is based on the Intrade odds on individual Senate races.)

• Over in the House, it looks like the GOP will re-take the House, with a majority ranging from 25 seats (230-205) to 33 seats (234-201) 53 seats (244-191).

My forecast of Republican gains in the House is based on two indicators. The first is Scott Rasmussen’s generic congressional ballot, which has been polled weekly since January 11, 2009. The data points in the graph below represent the results of the poll, to date. Although the GOP enjoys a lead of 9 percentage points in the latest poll, my analysis indicates that there will be a slight reversal of GOP gains as more noncommittal voters choose sides. The solid black line, which is fitted to the data points, shows that the downward trend has begun. A separate statistical analysis yields the dashed black line, which points to a GOP lead of 6.7 percentage points (a 234-201 majority) when the polls close on November 2.

The second indicator of GOP prospects in the House is Obama’s degree of unpopularity. The following graph depicts the relationship between Obama’s net unpopularity (percentage strongly disapproving less percentage strongly approving) and the number of percentage points by which votes cast for GOP House candidates will exceed votes cast for Democrat candidates.

This graph is derived from the results of Rasmussen’s generic congressional ballot and presidential tracking poll. The points on the graph represent the weekly results of the two Rasmussen polls for January 8, 2009, through October 17, 2010. If Obama’s unpopularity index stays at its current level of -10 -19 percentage points, the equation for the regression line in the graph yields a GOP advantage of 5.5 9.0 percentage points in the popular vote for House candidates. That translates into a majority of 230-205 244-191.

All of this assumes no major shocks between now and election day — nothing on the order of a terror attack, a specific terror threat, a scandal involving a major political figure, and so on.