There has been a split between the public polling and the internal polling in the recall of Scott Walker. As you can naturally expect, internal polling on the Democratic side shows a closer race. And that continues today with a poll from Celinda Lake showing a dead heat between Walker and Milwaukee mayor Tom Barrett, which each candidate getting 49% of the vote. Barrett has the lead among independents, according to the poll, 49-44.

It should be pointed out that no poll, public or internal, has shown Barrett with a lead yet. Nevertheless, there are some factors that indicate a tightening of the race. First of all, the internal polls, like this one from Lake, are newer. They are picking up on a more advanced state of the race. And there’s reason to believe that Barrett would improve; he’s only gone on the air with any kind of advertising against Walker in the last two weeks.

Second, the Walker campaign or allied Republicans have not released any polling countering the internals from Democrats. If they had good numbers, you would think they would show them.

Third: this brutal negative attack ad the Walker campaign just put out against Barrett, which is simply not something a campaign confident in its abilities to run out the clock with a lead would do.

Fourth: The debate last Friday showed Barrett very much on the offensive, and Walker trying to play defense. There’s another debate scheduled for tomorrow, which could raise more attention to the race.

Fifth: Turnout is expected to be extremely high, between 60-65%. The rule of thumb is that high turnout favors Democrats, though both sides appear energized for this recall fight. At any rate, that turnout would skew higher than the 2010 election, where Walker beat Barrett.

Sixth: Walker continues to generate bad headlines from the John Doe investigation into corruption in his various public offices. Today, new campaign finance reports show that Walker delivered another $100,000 into his legal defense fund. That brings the total to $160,000 just over the past six weeks. Andy Kroll has more on that.

And finally, more money is coming in on the Democratic side. The Progressive Change Campaign Committee has filled in some of the gap on the ground with a $100,000 donation to facilitate grassroots get-out-the-vote campaigning. The Democratic Governor’s Association has delivered $3 million to date. There’s nothing approaching parity, but Democrats supporting Barrett have close to what they need to get their message out.

There’s a new poll expected today from Marquette Law School, and it will be key to seeing if the public polling is following the trend found by Dem-allied groups.

UPDATE: And that Marquette Law School pool did no favors to Barrett. It shows Walker up 52-45 among likely voters (50-44 overall), extending his lead and pushing past a 50% mark that had been a stubborn ceiling for him in most other polling. The signs of tightening could be a mirage. This is a poll that has Obama up 51-43 over Romney in the general election, so I doubt it’s a Republican-heavy sample.