No. Even if the second round was Jospin-Le Pen, I guess the margin would have been somewhat closer provided a small majority of the conservative voters would have chosen Le Pen and a far more important faction wouldd have gone fishing on election day. But he would have lost.
Unlike, probably, other right-wing populist leaders in Europe, Le Pen has managed to secure a sizeable fraction of the French electorate, but he is positively hated by some 40% of the population and feared by another 35 %. Remain 5 % of hardcore extemist voters, 10 % who vote Le Pen as some form of protest (many Le Pen voters have voted previously for the Communists...) and 5 % of conservatives who despise le Pen but would rather have Belzebuth for President than a Socialist.
It's not only the racism and antisemitism, even if, of course, it plays a major role in Le Pen's isolation. His ideology has its roots in the most shameful times of French history (Vichy and the Algerian coup) and, on top of everything, he's a radical Thatecherite when it comes to economics in a country where (for good and worse), egalitarian values are treasured byt the majority. The illegitimate child of Sarah Palin and Pat Robertson, raised by David Duke, would not be worse. As a sidenote, it is the honor of the French conservatives to have consistently refused any deal with the Front National.
Then again, when Le Pen passes away, his far more subtle daughter will most probably take the lead, and I'm pretty sure that a UMP-FN alliance would not be impossible...