WASHINGTON  Nasty charges of bribery. Senators cut off midspeech. Accusations of politics put over patriotism. Talk of double-crosses. A nonagenarian forced to the floor after midnight for multiple procedural votes.

In the heart of the holiday season, Senate Republicans and Democrats are at one another’s throats as the health care overhaul reaches its climactic votes. A year that began with hopes of new post-partisanship has indeed produced change: Things have gotten worse.

Enmity and acrimony are coursing through a debate with tremendous consequences for both sides as well as for the legislative agenda in the months ahead.

Should Democrats prevail, it will put an exclamation point on an eventful first year of their control of Congress and the White House and leave Republicans on the Napoleonic side of what one predicted could be President Obama’s Waterloo. A Republican victory would invigorate an opposition party that was back on its heels at the beginning of 2009 and would strike a crushing blow to Democrats and their claims to governing.