PRINCETON, NJ — Barack Obama leads John McCain, 50% to 42% among registered voters in the latest Gallup Poll Daily tracking update for Thursday, Friday, and Saturday — just one point shy of his strongest showing of the year.

These results, from Sept. 25-27, span the time period since John McCain made the announcement that he was temporarily suspending his campaign and returning to Washington to work for a bipartisan solution to the financial crisis, and since Congressional leaders first announced progress towards the resolution of a financial bailout bill. The results also include one complete day (Saturday) after the first presidential debate on Friday night. McCain had reached a point where he was tied with Obama earlier in the week, but Obama has gained steadily in each of the last three days’ reports. Overall, Obama has gained four percentage points over the last three days, while McCain has lost four points, for an eight-point swing in the “gap” or margin.

The full impact of the debate and its aftermath will not be reflected in the tracking data until Tuesday’s report, which will be based on interviewing conducted Saturday, Sunday, and Monday. Still, Gallup’s one-day read on the standing of the two candidates on Saturday suggests that Obama held the lead over McCain among registered voters that night, just as he had for the two previous nights.

Obama reached an eight-point lead or higher twice before, once after his highly publicized foreign tour to Afghanistan, Iraq, and Europe in July, and once after the Democratic National Convention. In both of these instances, Obama’s relatively large lead was short-lived; McCain came charging back to tie the race in both cases. Thus history would suggest the potential for future shifts in voter preferences and for McCain to bounce back once again.

Additionally, major news events relating to the campaign will be forthcoming over the next several weeks — including the final resolution of Congress’ efforts to pass a financial bailout bill and three more debates (two presidential, and one vice presidential), all of which could have the potential for future shifts in voter preferences. Obama has held at least a moderate edge over McCain for the vast majority of the days of Gallup Poll Daily tracking since June, and overall has led by an average of about three points in the over 100,000 interviews conducted by Gallup during this time period. (To view the complete trend since March 7, 2008, click here.) — Frank Newport

(Click here to see how the race currently breaks down by demographic subgroup.)