* Trump to address Republican Senators on tax
* Fight with Corker overshadows meeting
* Ryan urges House tax bill by Thanksgiving (Adds Ryan quotes, details on tax plan)
WASHINGTON, Oct 24 (Reuters) - President Donald Trump headed for talks with Republican senators on Tuesday to try to build consensus for proposed tax cuts in a meeting that was overshadowed by an exchange of insults between the president and one of the lawmakers.
Trump has asked his fellow Republicans who control Congress to pass a package of tax cuts, including a deep reduction in the corporate income tax, by year's end.
But hours before he was to promote the tax plan at a weekly lunch for Republican senators on Capitol Hill, Trump engaged in a distracting tussle with one of those lawmakers: Bob Corker, a leading fiscal hawk and the head of the Senate Foreign Relations Committee.
"Bob Corker, who ... couldn't get elected dog catcher in Tennessee, is now fighting Tax Cuts," Trump wrote on Twitter, later adding that the senator is "incompetent."
Alienating any members of his own party could be costly for Trump's legislative initiatives in the Senate because Republicans control the chamber by just a slim 52-48 margin.
Corker warned Trump in television interviews against interfering in congressional efforts to finalize the legislation to cut taxes and called the president's visit with Senate Republicans "a photo op."
"Hopefully, the White House will step aside and let that occur in a normal process," the Tennessee Republican told NBC's "Today" program. "That's the best way for us to have success."
Corker also described Trump in a Twitter post as "an utterly untruthful president," and in television interviews accused Trump of debasing the United States.
House of Representatives Speaker Paul Ryan urged reporters to ignore the Trump-Corker spat and concentrate on the tax plan.
"Put this Twitter dispute aside. The fact is we have an historic chance of fixing this tax code," Ryan said.
Ryan added that he knows Corker well and predicted that the senator is "going to vote for tax reform."
Ryan said he wants the House to pass the Republican tax cut bill by the Nov. 23 U.S. Thanksgiving holiday, echoing Trump's call to speed up the party's efforts to get the measure approved before year's end.
Securing congressional passage of his tax plan is critically important to Trump, who has yet to get major legislation through Congress since taking office in January, including a healthcare overhaul he promised as a candidate last year. Tax cuts were another of Trump's campaign pledges.
The White House argues that tax cuts are needed to boost economic growth and create jobs, but has shown sensitivity in recent weeks to arguments that it is endangering America's long-term fiscal health.
One of the key elements of the proposal is to slash the corporate income tax rate to 20 percent from 35 percent. While the broad parameters of the tax proposal have been made public, detailed legislation has not yet been unveiled.
Democrats have painted Trump's plan, with its $6 trillion in tax cuts, as a gift to the rich and corporate America that would balloon the federal deficit.
Trump promised on Monday to protect a popular retirement program as Republican lawmakers seek ways to pay for the proposed cuts.
(Additional reporting by Makini Brice; Writing by Alistair Bell; Editing by Will Dunham)