The Republican presidential primary has had a seriously negative impact on both the GOP brand and that of front runner Mitt Romney. From NBC First Read about their newest national poll:

Four in 10 of all adults say the GOP nominating process has given them a less favorable impression of the Republican Party, versus just slightly more than one in 10 with a more favorable opinion.

Additionally, when asked to describe the GOP nominating battle in a word or phrase, nearly 70 percent of respondents – including six in 10 independents and even more than half of Republicans – answered with a negative comment.

Some examples of these negative comments from Republicans: “Unenthusiastic,” “discouraged,” “lesser of two evils,” “painful,” “disappointed,” “poor choices,” “concerned,” “underwhelmed,” “uninspiring” and “depressed.”

The primary has also driven up Mitt Romney’s personal unfavorable numbers. The NBC/WSJ poll found that 28 percent had positive feelings about Romney, while 39 percent had negative feelings about him. This is a noticeable increase in negative opinions about Romney over the past five months of the primary. The same poll in November found 26 percent viewed Romney positively and only 30 percent viewed him negatively.

This fits with the general pattern about Romney’s favorability rating we have seen in almost all other polls. Despite having to spend tens of millions to define himself, Romney has become increasingly unpopular as this primary fight has gone on; his favorability rating is now strongly net negative in virtually every poll.

Given how damaging this primary has been to the Republican brand and its likely nominee, we are now starting to see even very conservative Republican officials like Eric Cantor and Tom Coburn endorse Romney, hoping to bring the primary fight to a quicker conclusion.