Across Iowa, challengers take digs at Gingrich

>>> to presidential politics now. a major endorsement today for mitt romney from iowa's largest newspaper. it is a shot in the arm for the romney campaign, hoping to stem the recent surge of newt gingrich . nbc's mike viqueira with the latest.

>> reporter: entering the homestretch in iowa, candidates in the back of the pack are racing to catch up. rick perry and michele bachmann are blanketing the state on bus tours, stopping to greet voters. and delivering attacks on front-runner newt gingrich .

>> trying to sound like a conservative, but sounding more like a 30-year establishment washington beat insider that he is.

>> reporter: today, mitt romney questioned gingrich's ability to lead.

>> he has been unreliable in those settings and zany. i wouldn't think you would call mirrors in space to light highways at night particularly practical or lunar colony a practical idea, not at a stage like this.

>> reporter: this as gingrich invited more controversy, speaking out in favor of abolishing some courts, allowing presidents to ignore judicial rulings and empowering congress to subpoena judges.

>> would you send the capital police to arrest him?

>> if you had to. or you instruct the justice department to send u.s. martial.

>> reporter: in the past two days, romney scored a string of endorsements, including the " des moines register ," though the paper's record of picking winners is mixed. john mccain was their choice in 2008 over the eventual caucus winner conservative mike huckabee . the backing comes as a welcome boost for the romney campaign.

>> all we have seen and heard from governor romney , he was very measured, very focused on what we think is the most pressing issue in front of all of us, the economy.

>> reporter: and, lester, you may be surprised to learn that newt gingrich pronounced himself delighted that the des moines register endorsed romney , he called it a solidly liberal paper and pointed out that the manchester union leader , much more conservative editorially, endorsed him.

>> mike viqueira at the white house . mike, thanks.